Backport #25567

Ref:

* https://github.com/go-gitea/gitea/issues/25377#issuecomment-1609757289

And some sub-commands like "generate" / "docs", they do not need to use
the ini config

Backport #25330

# The problem

There were many "path tricks":

* By default, Gitea uses its program directory as its work path
* Gitea tries to use the "work path" to guess its "custom path" and
"custom conf (app.ini)"
* Users might want to use other directories as work path
* The non-default work path should be passed to Gitea by GITEA_WORK_DIR
or "--work-path"
* But some Gitea processes are started without these values
    * The "serv" process started by OpenSSH server
    * The CLI sub-commands started by site admin
* The paths are guessed by SetCustomPathAndConf again and again
* The default values of "work path / custom path / custom conf" can be
changed when compiling

# The solution

* Use `InitWorkPathAndCommonConfig` to handle these path tricks, and use
test code to cover its behaviors.
* When Gitea's web server runs, write the WORK_PATH to "app.ini", this
value must be the most correct one, because if this value is not right,
users would find that the web UI doesn't work and then they should be
able to fix it.
* Then all other sub-commands can use the WORK_PATH in app.ini to
initialize their paths.
* By the way, when Gitea starts for git protocol, it shouldn't output
any log, otherwise the git protocol gets broken and client blocks
forever.

The "work path" priority is: WORK_PATH in app.ini > cmd arg --work-path
> env var GITEA_WORK_DIR > builtin default

The "app.ini" searching order is: cmd arg --config > cmd arg "work path
/ custom path" > env var "work path / custom path" > builtin default


## ⚠️ BREAKING

If your instance's "work path / custom path / custom conf" doesn't meet
the requirements (eg: work path must be absolute), Gitea will report a
fatal error and exit. You need to set these values according to the
error log.

## ⚠️ Breaking

The `log.<mode>.<logger>` style config has been dropped. If you used it,
please check the new config manual & app.example.ini to make your
instance output logs as expected.

Although many legacy options still work, it's encouraged to upgrade to
the new options.

The SMTP logger is deleted because SMTP is not suitable to collect logs.

If you have manually configured Gitea log options, please confirm the
logger system works as expected after upgrading.

## Description

Close #12082 and maybe more log-related issues, resolve some related
FIXMEs in old code (which seems unfixable before)

Just like rewriting queue #24505 : make code maintainable, clear legacy
bugs, and add the ability to support more writers (eg: JSON, structured
log)

There is a new document (with examples): `logging-config.en-us.md`

This PR is safer than the queue rewriting, because it's just for
logging, it won't break other logic.

## The old problems

The logging system is quite old and difficult to maintain:
* Unclear concepts: Logger, NamedLogger, MultiChannelledLogger,
SubLogger, EventLogger, WriterLogger etc
* Some code is diffuclt to konw whether it is right:
`log.DelNamedLogger("console")` vs `log.DelNamedLogger(log.DEFAULT)` vs
`log.DelLogger("console")`
* The old system heavily depends on ini config system, it's difficult to
create new logger for different purpose, and it's very fragile.
* The "color" trick is difficult to use and read, many colors are
unnecessary, and in the future structured log could help
* It's difficult to add other log formats, eg: JSON format
* The log outputer doesn't have full control of its goroutine, it's
difficult to make outputer have advanced behaviors
* The logs could be lost in some cases: eg: no Fatal error when using
CLI.
* Config options are passed by JSON, which is quite fragile.
* INI package makes the KEY in `[log]` section visible in `[log.sub1]`
and `[log.sub1.subA]`, this behavior is quite fragile and would cause
more unclear problems, and there is no strong requirement to support
`log.<mode>.<logger>` syntax.


## The new design

See `logger.go` for documents.


## Screenshot

<details>


![image](https://github.com/go-gitea/gitea/assets/2114189/4462d713-ba39-41f5-bb08-de912e67e1ff)


![image](https://github.com/go-gitea/gitea/assets/2114189/b188035e-f691-428b-8b2d-ff7b2199b2f9)


![image](https://github.com/go-gitea/gitea/assets/2114189/132e9745-1c3b-4e00-9e0d-15eaea495dee)

</details>

## TODO

* [x] add some new tests
* [x] fix some tests
* [x] test some sub-commands (manually ....)

---------

Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Giteabot <teabot@gitea.io>

This PR will merge 3 Init functions on setting packages as 1 and
introduce an options struct.

The idea is to use a Layered Asset File-system (modules/assetfs/layered.go)

For example: when there are 2 layers: "custom", "builtin", when access
to asset "my/page.tmpl", the Layered Asset File-system will first try to
use "custom" assets, if not found, then use "builtin" assets.

This approach will hugely simplify a lot of code, make them testable.

Other changes:

* Simplify the AssetsHandlerFunc code
* Simplify the `gitea embedded` sub-command code

---------

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

Some bugs caused by less unit tests in fundamental packages. This PR
refactor `setting` package so that create a unit test will be easier
than before.

- All `LoadFromXXX` files has been splited as two functions, one is
`InitProviderFromXXX` and `LoadCommonSettings`. The first functions will
only include the code to create or new a ini file. The second function
will load common settings.
- It also renames all functions in setting from `newXXXService` to
`loadXXXSetting` or `loadXXXFrom` to make the function name less
confusing.
- Move `XORMLog` to `SQLLog` because it's a better name for that.

Maybe we should finally move these `loadXXXSetting` into the `XXXInit`
function? Any idea?

---------

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

Change all license headers to comply with REUSE specification.

Fix #16132

Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>

Found using
`find . -type f -name '*.go' -print -exec vim {} -c
':%s/fmt\.Errorf(\(.*\)%v\(.*\)err/fmt.Errorf(\1%w\2err/g' -c ':wq' \;`

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

The recovery, API, Web and package frameworks all create their own HTML
Renderers. This increases the memory requirements of Gitea
unnecessarily with duplicate templates being kept in memory.

Further the reloading framework in dev mode for these involves locking
and recompiling all of the templates on each load. This will potentially
hide concurrency issues and it is inefficient.

This PR stores the templates renderer in the context and stores this
context in the NormalRoutes, it then creates a fsnotify.Watcher
framework to watch files.

The watching framework is then extended to the mailer templates which
were previously not being reloaded in dev.

Then the locales are simplified to a similar structure.

Fix #20210 
Fix #20211
Fix #20217

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

Go 1.17 and later use modern `//go:build` constraints, the old `// +build:` constraints should be removed.

* gofumpt -w -l .

* gofumpt -w -l -extra .

* Add linter

* manual fix

* change make fmt

* Improve install code to avoid low-level mistakes.

If a user tries to do a re-install in a Gitea database, they gets a warning and double check.
When Gitea runs, it never create empty app.ini automatically.

Also some small (related) refactoring:

* Refactor db.InitEngine related logic make it more clean (especially for the install code)
* Move some i18n strings out from setting.go to make the setting.go can be easily maintained.
* Show errors in CLI code if an incorrect app.ini is used.
* APP_DATA_PATH is created when installing, and checked when starting (no empty directory is created any more).

* Add bundle download

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Fix fmt

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Fix build tags

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Download specific commit

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Retry rename on lock induced failures

Due to external locking on Windows it is possible for an
os.Rename to fail if the files or directories are being
used elsewhere.

This PR simply suggests retrying the rename again similar
to how we handle the os.Remove problems.

Fix #16427

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

* resolve CI fail

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

* draft

* Implement extract command

* Fix nits and force args on extract

* Add !bindata stub, support Windows, fmt

* fix vendored flag

* Remove leading slash for matching

* Add docs

* Fix typos

* Add embedded view command

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>