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>

These two functions are similiar, merge them.

Add nakedret, unconvert, wastedassign, stylecheck and nolintlint linters to improve code readability

- nakedret - https://github.com/alexkohler/nakedret - nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.
- unconvert - https://github.com/mdempsky/unconvert - Remove unnecessary type conversions
- wastedassign - https://github.com/sanposhiho/wastedassign -  wastedassign finds wasted assignment statements.
- notlintlint -  Reports ill-formed or insufficient nolint directives
- stylecheck - https://staticcheck.io/docs/checks/#ST - keep style consistent
  - excluded: [ST1003 - Poorly chosen identifier](https://staticcheck.io/docs/checks/#ST1003) and [ST1005 - Incorrectly formatted error string](https://staticcheck.io/docs/checks/#ST1005)

* Fix inconsistency in doctor output

- Use `logger.Info` instead of `logger.Warn` when no errors were found.

* Update modules/doctor/fix16961.go

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

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

* Remove `db.DefaultContext` usage in routers, use `ctx` directly

* Use `ctx` directly if there is one, remove some `db.DefaultContext` in `services`

* Use ctx instead of db.DefaultContext for `cmd` and some `modules` packages

* fix incorrect context usage

* gofumpt -w -l .

* gofumpt -w -l -extra .

* Add linter

* manual fix

* change make fmt

This PR continues the work in #17125 by progressively ensuring that git
commands run within the request context.

This now means that the if there is a git repo already open in the context it will be used instead of reopening it.

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

Found via `codespell -q 3 -S ./options/locale,./vendor -L ba,pullrequest,pullrequests,readby,te,unknwon`

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

* Some refactors related repository model

* Move more methods out of repository

* Move repository into models/repo

* Fix test

* Fix test

* some improvements

* Remove unnecessary function

* go build / format tools
* re-format imports

* Move unit into models/unit/

* Rename unit.UnitType as unit.Type

There was a serious issue with the `gitea dump` command in 1.14.3-1.14.6 which led to corruption of the `config` field of the `repo_unit` table. 

This PR adds a doctor command to attempt to fix the broken repo_units. Users affected by #16961 should run:

```
gitea doctor --fix --run fix-broken-repo-units
```

Fix #16961

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