This PR adds a [Conda](https://conda.io/) package registry.

Close #13539.

Co-authored by: @lunny @appleboy @fuxiaohei and others.

Related projects:
- https://gitea.com/gitea/actions-proto-def
- https://gitea.com/gitea/actions-proto-go
- https://gitea.com/gitea/act
- https://gitea.com/gitea/act_runner

### Summary

The target of this PR is to bring a basic implementation of "Actions",
an internal CI/CD system of Gitea. That means even though it has been
merged, the state of the feature is **EXPERIMENTAL**, and please note
that:

- It is disabled by default;
- It shouldn't be used in a production environment currently;
- It shouldn't be used in a public Gitea instance currently;
- Breaking changes may be made before it's stable.

**Please comment on #13539 if you have any different product design
ideas**, all decisions reached there will be adopted here. But in this
PR, we don't talk about **naming, feature-creep or alternatives**.

### ⚠️ Breaking

`gitea-actions` will become a reserved user name. If a user with the
name already exists in the database, it is recommended to rename it.

### Some important reviews

- What is `DEFAULT_ACTIONS_URL` in `app.ini` for?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1055954954
- Why the api for runners is not under the normal `/api/v1` prefix?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1061173592
- Why DBFS?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1061301178
- Why ignore events triggered by `gitea-actions` bot?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1063254103
- Why there's no permission control for actions?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1090229868

### What it looks like

<details>

#### Manage runners

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205870657-c72f590e-2e08-4cd4-be7f-2e0abb299bbf.png">

#### List runs

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205872794-50fde990-2b45-48c1-a178-908e4ec5b627.png">


#### View logs

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205872501-9b7b9000-9542-4991-8f55-18ccdada77c3.png">



</details>

### How to try it

<details>

#### 1. Start Gitea

Clone this branch and [install from
source](https://docs.gitea.io/en-us/install-from-source).

Add additional configurations in `app.ini` to enable Actions:

```ini
[actions]
ENABLED = true
```

Start it.

If all is well, you'll see the management page of runners:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205877365-8e30a780-9b10-4154-b3e8-ee6c3cb35a59.png">


#### 2. Start runner

Clone the [act_runner](https://gitea.com/gitea/act_runner), and follow
the
[README](https://gitea.com/gitea/act_runner/src/branch/main/README.md)
to start it.

If all is well, you'll see a new runner has been added:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205878000-216f5937-e696-470d-b66c-8473987d91c3.png">

#### 3. Enable actions for a repo

Create a new repo or open an existing one, check the `Actions` checkbox
in settings and submit.

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205879705-53e09208-73c0-4b3e-a123-2dcf9aba4b9c.png">
<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205879383-23f3d08f-1a85-41dd-a8b3-54e2ee6453e8.png">

If all is well, you'll see a new tab "Actions":

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205881648-a8072d8c-5803-4d76-b8a8-9b2fb49516c1.png">

#### 4. Upload workflow files

Upload some workflow files to `.gitea/workflows/xxx.yaml`, you can
follow the [quickstart](https://docs.github.com/en/actions/quickstart)
of GitHub Actions. Yes, Gitea Actions is compatible with GitHub Actions
in most cases, you can use the same demo:

```yaml
name: GitHub Actions Demo
run-name: ${{ github.actor }} is testing out GitHub Actions 🚀
on: [push]
jobs:
  Explore-GitHub-Actions:
    runs-on: ubuntu-latest
    steps:
      - run: echo "🎉 The job was automatically triggered by a ${{ github.event_name }} event."
      - run: echo "🐧 This job is now running on a ${{ runner.os }} server hosted by GitHub!"
      - run: echo "🔎 The name of your branch is ${{ github.ref }} and your repository is ${{ github.repository }}."
      - name: Check out repository code
        uses: actions/checkout@v3
      - run: echo "💡 The ${{ github.repository }} repository has been cloned to the runner."
      - run: echo "🖥️ The workflow is now ready to test your code on the runner."
      - name: List files in the repository
        run: |
          ls ${{ github.workspace }}
      - run: echo "🍏 This job's status is ${{ job.status }}."
```

If all is well, you'll see a new run in `Actions` tab:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205884473-79a874bc-171b-4aaf-acd5-0241a45c3b53.png">

#### 5. Check the logs of jobs

Click a run and you'll see the logs:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205884800-994b0374-67f7-48ff-be9a-4c53f3141547.png">

#### 6. Go on

You can try more examples in [the
documents](https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions)
of GitHub Actions, then you might find a lot of bugs.

Come on, PRs are welcome.

</details>

See also: [Feature Preview: Gitea
Actions](https://blog.gitea.io/2022/12/feature-preview-gitea-actions/)

---------

Co-authored-by: a101211279 <1012112796@qq.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: ChristopherHX <christopher.homberger@web.de>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>

Fixes #22571

Co-authored-by: Yarden Shoham <hrsi88@gmail.com>

This PR adds a task to the cron service to allow garbage collection of
LFS meta objects. As repositories may have a large number of
LFSMetaObjects, an updated column is added to this table and it is used
to perform a generational GC to attempt to reduce the amount of work.
(There may need to be a bit more work here but this is probably enough
for the moment.)

Fix #7045

Signed-off-by: Andrew Thornton <art27@cantab.net>

closes #13585
fixes #9067
fixes #2386
ref #6226
ref #6219
fixes #745

This PR adds support to process incoming emails to perform actions.
Currently I added handling of replies and unsubscribing from
issues/pulls. In contrast to #13585 the IMAP IDLE command is used
instead of polling which results (in my opinion 😉) in cleaner code.

Procedure:
- When sending an issue/pull reply email, a token is generated which is
present in the Reply-To and References header.
- IMAP IDLE waits until a new email arrives
- The token tells which action should be performed

A possible signature and/or reply gets stripped from the content.

I added a new service to the drone pipeline to test the receiving of
incoming mails. If we keep this in, we may test our outgoing emails too
in future.

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

If user has reached the maximum limit of repositories:

- Before
  - disallow create
  - allow fork without limit
- This patch:
  - disallow create
  - disallow fork
- Add option `ALLOW_FORK_WITHOUT_MAXIMUM_LIMIT` (Default **true**) :
enable this allow user fork repositories without maximum number limit

fixed https://github.com/go-gitea/gitea/issues/21847

Signed-off-by: Xinyu Zhou <i@sourcehut.net>

For a long time Gitea has tested PR patches using a git apply --check
method, and in fact prior to the introduction of a read-tree assisted
three-way merge in #18004, this was the only way of checking patches.

Since #18004, the git apply --check method has been a fallback method,
only used when the read-tree three-way merge method has detected a
conflict. The read-tree assisted three-way merge method is much faster
and less resource intensive method of detecting conflicts. #18004 kept
the git apply method around because it was thought possible that this
fallback might be able to rectify conflicts that the read-tree three-way
merge detected. I am not certain if this could ever be the case.

Given the uncertainty here and the now relative stability of the
read-tree method - this PR makes using this fallback optional and
disables it by default. The hope is that users will not notice any
significant difference in conflict detection and we will be able to
remove the git apply fallback in future, and/or improve the read-tree
three-way merge method to catch any conflicts that git apply method
might have been able to fix.

An additional benefit is that patch checking should be significantly
less resource intensive and much quicker.

(See
https://github.com/go-gitea/gitea/issues/22083\#issuecomment-1347961737)

Ref #22083

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: KN4CK3R <admin@oldschoolhack.me>

Gitea will migrate the database model version automatically, but it
should be able to be disabled and keep Gitea shutdown if the version is
not matched.

Found via codespell

Unfortunately the fallback configuration code for [mailer] that were
added in #18982 are incorrect. When you read a value from an ini section
that key is added. This leads to a failure of the fallback mechanism.
Further there is also a spelling mistake in the startTLS configuration.

This PR restructures the mailer code to first map the deprecated
settings on to the new ones - and then use ini.MapTo to map those on to
the struct with additional validation as necessary.

Ref #21744

Signed-off-by: Andrew Thornton <art27@cantab.net>

Enable this to require captcha validation for user login. You also must
enable `ENABLE_CAPTCHA`.

Summary:
- Consolidate CAPTCHA template
- add CAPTCHA handle and context
- add `REQUIRE_CAPTCHA_FOR_LOGIN` config and docs
- Consolidate CAPTCHA set-up and verification code 

Partially resolved #6049 

Signed-off-by: Xinyu Zhou <i@sourcehut.net>
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Andrew Thornton <art27@cantab.net>

This patch provide a mechanism to disable RSS/Atom feed.

Signed-off-by: Xinyu Zhou <i@sourcehut.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: 6543 <6543@obermui.de>

This PR enhances the CORS middleware usage by allowing for the headers
to be configured in `app.ini`.

Fixes #21746

Co-authored-by: KN4CK3R <admin@oldschoolhack.me>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

Attempt clarify the AppWorkPath in the documentation by using different
notation and adding a section to the start of the cheat sheet.

Fix #21523

Signed-off-by: Andrew Thornton <art27@cantab.net>

Signed-off-by: Andrew Thornton <art27@cantab.net>

Related #20471

This PR adds global quota limits for the package registry. Settings for
individual users/orgs can be added in a seperate PR using the settings
table.

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

This patch provide a mechanism to disable
[sitemap](https://github.com/go-gitea/gitea/pull/18407).

Signed-off-by: Xinyu Zhou <i@sourcehut.net>
Co-authored-by: 6543 <6543@obermui.de>

Add allowed values: `repo.projects`

Only load SECRET_KEY and INTERNAL_TOKEN if they exist.
Never write the config file if the keys do not exist, which was only a fallback for Gitea upgraded from < 1.5

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

Previously, the docs seemed to suggest that you can disable the API
completely by setting `ENABLE_SWAGGER=false`.
This is not the case.

This PR adds mathematical rendering with KaTeX.

The first step is to add a Goldmark extension that detects the latex
(and tex) mathematics delimiters.

The second step to make this extension only run if math support is
enabled.

The second step is to then add KaTeX CSS and JS to the head which will
load after the dom is rendered.

Fix #3445

Signed-off-by: Andrew Thornton <art27@cantab.net>

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

Adds a new option to only show relevant repo's on the explore page, for bigger Gitea instances like Codeberg this is a nice option to enable to make the explore page more populated with unique and "high" quality repo's. A note is shown that the results are filtered and have the possibility to see the unfiltered results.

Co-authored-by: vednoc <vednoc@protonmail.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: 6543 <6543@obermui.de>

This PR adds functionality to allow Gitea to sit behind an
HAProxy and HAProxy protocolled connections directly.

Fix #7508

Signed-off-by: Andrew Thornton <art27@cantab.net>

This adds support for getting the user's full name from the reverse
proxy in addition to username and email.

Tested locally with caddy serving as reverse proxy with Tailscale
authentication.

Signed-off-by: Will Norris <will@tailscale.com>

Signed-off-by: Will Norris <will@tailscale.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

https://mcaptcha.org/

Co-authored-by: Felipe Leopoldo Sologuren Gutiérrez <fsologureng@users.noreply.github.com>

* increase default page sizes to 20
* adjust docs to reflect that the setting is used all over the place
* fix tests

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

- Follow up of #20616. Add a note about this in the config cheat
sheet, given there's no dedicated page for this.

* `PROTOCOL`: can be smtp, smtps, smtp+startls, smtp+unix, sendmail, dummy
* `SMTP_ADDR`: domain for SMTP, or path to unix socket
* `SMTP_PORT`: port for SMTP; defaults to 25 for `smtp`, 465 for `smtps`, and 587 for `smtp+startls`
* `ENABLE_HELO`, `HELO_HOSTNAME`: reverse `DISABLE_HELO` to `ENABLE_HELO`; default to false + system hostname
* `FORCE_TRUST_SERVER_CERT`: replace the unclear `SKIP_VERIFY`
* `CLIENT_CERT_FILE`, `CLIENT_KEY_FILE`, `USE_CLIENT_CERT`: clarify client certificates here

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

Add configuration to enable/disable download source from UI.

Co-authored-by: zeripath <art27@cantab.net>

Co-authored-by: Andrew Thornton <art27@cantab.net>

Before, the combination of AllowedDomains/BlockedDomains/AllowLocalNetworks is confusing.

This PR adds tests for the logic, clarify the behaviors.

* Add git.HOME_PATH

* add legacy file check

* Apply suggestions from code review

Co-authored-by: zeripath <art27@cantab.net>

* pass env GNUPGHOME to git command, move the existing .gitconfig to new home, make the fix for 1.17rc more clear.

* set git.HOME_PATH for docker images to default HOME

* Revert "set git.HOME_PATH for docker images to default HOME"

This reverts commit f120101ddc.

* force Gitea to use a stable GNUPGHOME directory

* extra check to ensure only process dir or symlink for legacy files

* refactor variable name

* The legacy dir check (for 1.17-rc1) could be removed with 1.18 release, since users should have upgraded from 1.17-rc to 1.17-stable

* Update modules/git/git.go

Co-authored-by: Steven Kriegler <61625851+justusbunsi@users.noreply.github.com>

* remove initFixGitHome117rc

* Update git.go

* Update docs/content/doc/advanced/config-cheat-sheet.en-us.md

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Steven Kriegler <61625851+justusbunsi@users.noreply.github.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

Unfortunately it appears that 2048 bit RSA keys can occasionally be created in such
a way that they appear to have 2047 bit length. This PR simply changes our defaults to
allow these.

Fix #20249

Signed-off-by: Andrew Thornton <art27@cantab.net>

Synced the list to what is allowed on GitHub currently.

- The language doesn't have >= 25% translation on crowdin and therefor
was automatically removed from Gitea.
- Ref: f91092453e

- Completely remove U2F support from 1.18.0, 1.17.0 will be the last
release that U2F is somewhat supported. Users who used U2F would already
be warned about using U2F for a while now and should hopefully already
be migrated. But starting 1.18 definitely remove it.

* go.mod: add go-fed/{httpsig,activity/pub,activity/streams} dependency

go get github.com/go-fed/activity/streams@master
go get github.com/go-fed/activity/pub@master
go get github.com/go-fed/httpsig@master

* activitypub: implement /api/v1/activitypub/user/{username} (#14186)

Return informations regarding a Person (as defined in ActivityStreams
https://www.w3.org/TR/activitystreams-vocabulary/#dfn-person).

Refs: https://github.com/go-gitea/gitea/issues/14186

Signed-off-by: Loïc Dachary <loic@dachary.org>

* activitypub: add the public key to Person (#14186)

Refs: https://github.com/go-gitea/gitea/issues/14186

Signed-off-by: Loïc Dachary <loic@dachary.org>

* activitypub: go-fed conformant Clock instance

Signed-off-by: Loïc Dachary <loic@dachary.org>

* activitypub: signing http client

Signed-off-by: Loïc Dachary <loic@dachary.org>

* activitypub: implement the ReqSignature middleware

Signed-off-by: Loïc Dachary <loic@dachary.org>

* activitypub: hack_16834

Signed-off-by: Loïc Dachary <loic@dachary.org>

* Fix CI checks-backend errors with go mod tidy

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Change 2021 to 2022, properly format package imports

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Run make fmt and make generate-swagger

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Use Gitea JSON library, add assert for pkp

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Run make fmt again, fix err var redeclaration

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Remove LogSQL from ActivityPub person test

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Assert if json.Unmarshal succeeds

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Cleanup, handle invalid usernames for ActivityPub person GET request

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Rename hack_16834 to user_settings

Signed-off-by: Anthony Wang <ta180m@pm.me>

* Use the httplib module instead of http for GET requests

* Clean up whitespace with make fmt

* Use time.RFC1123 and make the http.Client proxy-aware

* Check if digest algo is supported in setting module

* Clean up some variable declarations

* Remove unneeded copy

* Use system timezone instead of setting.DefaultUILocation

* Use named constant for httpsigExpirationTime

* Make pubKey IRI #main-key instead of /#main-key

* Move /#main-key to #main-key in tests

* Implemented Webfinger endpoint.

* Add visible check.

* Add user profile as alias.

* Add actor IRI and remote interaction URL to WebFinger response

* fmt

* Fix lint errors

* Use go-ap instead of go-fed

* Run go mod tidy to fix missing modules in go.mod and go.sum

* make fmt

* Convert remaining code to go-ap

* Clean up go.sum

* Fix JSON unmarshall error

* Fix CI errors by adding @context to Person() and making sure types match

* Correctly decode JSON in api_activitypub_person_test.go

* Force CI rerun

* Fix TestActivityPubPersonInbox segfault

* Fix lint error

* Use @mariusor's suggestions for idiomatic go-ap usage

* Correctly add inbox/outbox IRIs to person

* Code cleanup

* Remove another LogSQL from ActivityPub person test

* Move httpsig algos slice to an init() function

* Add actor IRI and remote interaction URL to WebFinger response

* Update TestWebFinger to check for ActivityPub IRI in aliases

* make fmt

* Force CI rerun

* WebFinger: Add CORS header and fix Href -> Template for remote interactions

The CORS header is needed due to https://datatracker.ietf.org/doc/html/rfc7033#section-5 and fixes some Peertube <-> Gitea federation issues

* make lint-backend

* Make sure Person endpoint has Content-Type application/activity+json and includes PreferredUsername, URL, and Icon

Setting the correct Content-Type is essential for federating with Mastodon

* Use UTC instead of GMT

* Rename pkey to pubKey

* Make sure HTTP request Date in GMT

* make fmt

* dont drop err

* Make sure API responses always refer to username in original case

Copied from what I wrote on #19133 discussion: Handling username case is a very tricky issue and I've already encountered a Mastodon <-> Gitea federation bug due to Gitea considering Ta180m and ta180m to be the same user while Mastodon thinks they are two different users. I think the best way forward is for Gitea to only use the original case version of the username for federation so other AP software don't get confused.

* Move httpsig algs constant slice to modules/setting/federation.go

* Add new federation settings to app.example.ini and config-cheat-sheet

* Return if marshalling error

* Make sure Person IRIs are generated correctly

This commit ensures that if the setting.AppURL is something like "http://127.0.0.1:42567" (like in the integration tests), a trailing slash will be added after that URL.

* If httpsig verification fails, fix Host header and try again

This fixes a very rare bug when Gitea and another AP server (confirmed to happen with Mastodon) are running on the same machine, Gitea fails to verify incoming HTTP signatures. This is because the other AP server creates the sig with the public Gitea domain as the Host. However, when Gitea receives the request, the Host header is instead localhost, so the signature verification fails. Manually changing the host header to the correct value and trying the veification again fixes the bug.


* Revert "If httpsig verification fails, fix Host header and try again"

This reverts commit f53e46c721.

The bug was actually caused by nginx messing up the Host header when reverse-proxying since I didn't have the line `proxy_set_header Host $host;` in my nginx config for Gitea.

* Go back to using ap.IRI to generate inbox and outbox IRIs

* use const for key values

* Update routers/web/webfinger.go

* Use ctx.JSON in Person response to make code cleaner

* Revert "Use ctx.JSON in Person response to make code cleaner"

This doesn't work because the ctx.JSON() function already sends the response out and it's too late to edit the headers.

This reverts commit 95aad98897.

* Use activitypub.ActivityStreamsContentType for Person response Content Type

* Limit maximum ActivityPub request and response sizes to a configurable setting

* Move setting key constants to models/user/setting_keys.go

* Fix failing ActivityPubPerson integration test by checking the correct field for username

* Add a warning about changing settings that can break federation

* Add better comments

* Don't multiply Federation.MaxSize by 1<<20 twice

* Add more better comments

* Fix failing ActivityPubMissingPerson test

We now use ctx.ContextUser so the message printed out when a user does not exist is slightly different

* make generate-swagger

For some reason I didn't realize that /templates/swagger/v1_json.tmpl was machine-generated by make generate-swagger... I've been editing it by hand for three months! 🤦

* Move getting the RFC 2616 time to a separate function

* More code cleanup

* Update go-ap to fix empty liked collection and removed unneeded HTTP headers

* go mod tidy

* Add ed25519 to httpsig algorithms

* Use go-ap/jsonld to add @context and marshal JSON

* Change Gitea user agent from the default to Gitea/Version

* Use ctx.ServerError and remove all remote interaction code from webfinger.go

* Allow render HTML with css/js external links

* Fix bug because of filename escape chars

* Fix lint

* Update docs about new configuration item

* Fix bug of render HTML in sub directory

* Add CSP head for displaying iframe in rendering file

* Fix test

* Apply suggestions from code review

Co-authored-by: delvh <dev.lh@web.de>

* Some improvements

* some improvement

* revert change in SanitizerDisabled of external renderer

* Add sandbox for iframe and support allow-scripts and allow-same-origin

* refactor

* fix

* fix lint

* fine tune

* use single option RENDER_CONTENT_MODE, use sandbox=allow-scripts

* fine tune CSP

* Apply suggestions from code review

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

* Disable unnecessary mirroring elements

This mod fixes disabling unnecessary mirroring elements.

Related: https://github.com/go-gitea/gitea/pull/16957
Related: https://github.com/go-gitea/gitea/pull/13084
Author-Change-Id: IB#1105104

* Checkbox rendering disabled instead of hiding it

Fixes: 02b4505150
Related: https://github.com/go-gitea/gitea/pull/18527#pullrequestreview-878061913
Author-Change-Id: IB#1105104

* Update custom/conf/app.example.ini

Co-authored-by: silverwind <me@silverwind.io>

* Update docs/content/doc/advanced/config-cheat-sheet.en-us.md

Co-authored-by: silverwind <me@silverwind.io>

* Mirror filter removed only when whole mirroring feature is disabled

Fixes: 02b4505150
Related: https://github.com/go-gitea/gitea/pull/18527#discussion_r883268890
Author-Change-Id: IB#1105104

Co-authored-by: silverwind <me@silverwind.io>

* docs: update the ROOT documentation and error messages

* The documentation now reflects what happens in the
  setting/repository.go::newRepository function:
  filepath.Join(AppWorkPath, RepoRootPath) was missing.

* The error message displayed when RepoRootPath is not found now
  displays the value of RepoRootPath. Given the complexity of the
  construction of this value, only referring to it in the abstract
  is likely to be misleading to the Gitea admin trying to interpret
  the message.

Co-authored-by: delvh <dev.lh@web.de>

The issue was that only the actual title was converted to uppercase, but
not the prefix as specified in `WORK_IN_PROGRESS_PREFIXES`. As a result,
the following did not work:

    WORK_IN_PROGRESS_PREFIXES=Draft:,[Draft],WIP:,[WIP]

One possible workaround was:

    WORK_IN_PROGRESS_PREFIXES=DRAFT:,[DRAFT],WIP:,[WIP]

Then indeed one could use `Draft` (as well as `DRAFT`) in the title.
However, the link `Start the title with DRAFT: to prevent the pull request
from being merged accidentally.` showed the suggestion in uppercase; so
it is not possible to show it as `Draft`. This PR fixes it, and allows
to use `Draft` in `WORK_IN_PROGRESS_PREFIXES`.

Fixes #19779.

Co-authored-by: zeripath <art27@cantab.net>

* clarify what session provider 'db' does

* Also update session.PROVIDER in app.example.ini

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

To turn off the notification endpoint polling, the value should be set to -1, not 0.

Add statistic information for total user count, active user count, issue count and comment count for `/nodeinfo`