Backport #27231 #27259 manually

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

That ID is a "copy&paste" error, it conflicts with the
`initRepoMigrationStatusChecker` logic, which is the right function for
a real `#repo_migrating` element. That wrong ID causes incorrect page
navigation after installation.

HTML is not XML.

## TLDR

* Fix the broken page / broken image problem when click "Install"
* Close #20089
* Fix the Password Hash Algorithm display problem for #22942
* Close #23183
* Close #23184

## Details

### The broken page / broken image problem when click "Install"
(Redirect failed after install gitea #23184)

Before: when click "install", all new requests will fail, because the
server has been restarted. Users just see a broken page with broken
images, sometimes the server is not ready but the user would have been
redirect to "/user/login" page, then the users see a new broken page
(connection refused or something wrong ...)

After: only check InstallLock=true for necessary handlers, and sleep for
a while before restarting the server, then the browser has enough time
to load the "post-install" page. And there is a script to check whether
"/user/login" is ready, the user will only be redirected to the login
page when the server is ready.

### During new instance setup make 'Gitea Base URL' filled from
window.location.origin #20089

If the "app_url" input contains `localhost` (the default value from
config), use current window's location href as the `app_url` (aka
ROOT_URL)

### Fix the Password Hash Algorithm display problem for "Provide the
ability to set password hash algorithm parameters #22942"

Before: the UI shows `pbkdf2$50000$50`

<details>

![image](https://user-images.githubusercontent.com/2114189/221917143-e1e54798-1698-4fee-a18d-00c48081fc39.png)

</details>

After: the UI shows `pbkdf2`

<details>

![image](https://user-images.githubusercontent.com/2114189/221916999-97a15be8-2ebb-4a01-bf93-dac18e354fcc.png)

</details>

### GET data: net::ERR_INVALID_URL #23183

Cause by empty `data:` in `<link rel="manifest"
href="data:{{.ManifestData}}">`

---------

Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

This PR follows:
* #21986
* #22831

This PR also introduce customized HTML elements, which would also help
problems like:
* #17760
* #21429
* #21440

With customized HTML elements, there won't be any load-search-replace
operations, and it can avoid page flicking (which @silverwind cares a
lot).

Browser support:
https://developer.mozilla.org/en-US/docs/Web/API/Window/customElements

# FAQ

## Why the component has the prefix?

As usual, I would strongly suggest to add prefixes for our own/private
names. The dedicated prefix will avoid conflicts in the future, and it
makes it easier to introduce various 3rd components, like GitHub's
`relative-time` component. If there is no prefix, it's impossible to
introduce another public component with the same name in the future.

## Why the `custcomp.js` is loaded before HTML body? The `index.js` is
after HTML body.

Customized components must be registered before the content loading.
Otherwise there would be still some flicking.

`custcomp.js` should have its own dependencies and should be very light,
so it won't affect the page loading time too much.

## Why use `data-url` attribute but not use the `textContent`?

According to the standard, the `connectedCallback` occurs on the
tag-opening moment. The element's children are not ready yet.

## Why not use `{{.GuessCurrentOrigin $.ctx ...}}` to let backend decide
the absolute URL?

It's difficult for backend to guess the correct protocol(scheme)
correctly with zero configuration. Generating the absolute URL from
frontend can guarantee that the URL is 100% correct -- since the user is
visiting it.

# Screenshot

<details>

![image](https://user-images.githubusercontent.com/2114189/218256757-a267c8ba-3108-4755-9ae5-329f1b08f615.png)

</details>

* Add main aria landmark to templates
 * Adjust some titles to improve understanding of location in navigation

Contributed by @Forgejo

Use a new name for this template/frontend variable to make it distinct
from the server variable StaticURLPrefix.

* Enforce tab indendation in templates

This adds editorconfig-checker [1] to lint the template files so they
conform the editorconfig files. I fixed all current identation issues
using the fix mode of eclint [2] and some manual corrections.

We can extend this linting to other files later, for now I'd like this
PR to focus on HTML template files only.

[1] https://github.com/editorconfig-checker/editorconfig-checker
[2] https://github.com/jedmao/eclint

* fix indendation

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

* Add class to page content to unify top margin

Previously pages would individually set this margin but some didn't so
content would stick to the header without any space. Resolve this by
adding a new class that is added on all pages. The only place where we
remove this margin again is on the pages with menu or wrapper in the
header.

* fix admin notices

* fix team pages

* fix loading segment on gitgraph for arc-green

* fix last missing case

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

* Move install pages out of main macaron loop

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

* Update templates/post-install.tmpl

Co-authored-by: Lauris BH <lauris@nix.lv>

* remove prefetch

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

* Add a migrat service type switch page

* Improve translations

* remove images

* Fix images

* remove extra create repo button on dashboard

* Follow reviewers' opinions

* Fix frontend lint

* Remove wrong submit file

* Fix tests

* Adjust the size of image

* Apply suggestions from code review

Co-authored-by: 赵智超 <1012112796@qq.com>

* Remove username and password from migration of github/gitlab

* Improve docs

* Improve interface docs

Co-authored-by: 赵智超 <1012112796@qq.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

* static url

* add cors support for static resources

* [assets] work on the migration to configurable url for assets

Signed-off-by: Jakob Ackermann <das7pad@outlook.com>

* [misc] fix whitespace

Signed-off-by: Jakob Ackermann <das7pad@outlook.com>

* [assets] fix the loading of the manifest.json

It is generated dynamically, and as such can not be served by the cdn.

Signed-off-by: Jakob Ackermann <das7pad@outlook.com>

* Revert "add cors support for static resources"

This reverts commit 42f964fd18

Signed-off-by: Jakob Ackermann <das7pad@outlook.com>

* [docs] add the STATIC_URL_PREFIX option

Signed-off-by: Jakob Ackermann <das7pad@outlook.com>

* [docs] reverse-proxy: nginx: add two setups for STATIC_URL_PREFIX

Signed-off-by: Jakob Ackermann <das7pad@outlook.com>

* [assets] migrate the url of a new asset to the static url prefix

REF: f2a3abc683
Signed-off-by: Jakob Ackermann <das7pad@outlook.com>

* move migrating to backend

* add loading image when migrating and fix tests

* fix format

* fix lint

* add redis task queue support and improve docs

* add redis vendor

* fix vet

* add database migrations and fix app.ini sample

* add comments for task section on app.ini.sample

* Update models/migrations/v84.go

Co-Authored-By: lunny <xiaolunwen@gmail.com>

* Update models/repo.go

Co-Authored-By: lunny <xiaolunwen@gmail.com>

* move migrating to backend

* add loading image when migrating and fix tests

* fix fmt

* add redis task queue support and improve docs

* fix fixtures

* fix fixtures

* fix duplicate function on index.js

* fix tests

* rename repository statuses

* check if repository is being create when SSH request

* fix lint

* fix template

* some improvements

* fix template

* unified migrate options

* fix lint

* fix loading page

* refactor

* When gitea restart, don't restart the running tasks because we may have servel gitea instances, that may break the migration

* fix js

* Update models/repo.go

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

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

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* fix tests

* rename ErrTaskIsNotExist to ErrTaskDoesNotExist

* delete release after add one on tests to make it run happy

* fix tests

* fix tests

* improve codes

* fix lint

* fix lint

* fix migrations