The xorm `Sync2` has already been deprecated in favor of `Sync`,
so let's do the same inside the Gitea codebase.

Command used to replace everything:
```sh
for i in $(ag Sync2 --files-with-matches); do vim $i -c ':%sno/Sync2/Sync/g' -c ':wq'; done
```

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>

There are too many files in `models/migrations` folder so that I split
them into sub folders.

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>

* Add dismiss review feature

refs:
    https://github.blog/2016-10-12-dismissing-reviews-on-pull-requests/
    https://developer.github.com/v3/pulls/reviews/#dismiss-a-review-for-a-pull-request

* change modal ui and error message

* Add unDismissReview api

Signed-off-by: a101211279 <1012112796@qq.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>

* fix typo

* Migrate reviews when migrating repository from github

* fix lint

* Added test and migration when external user login

* fix test

* fix commented state

* Some improvements

* fix bug when get pull request and ref original author on code comments

* Fix migrated line; Added comment for review

* Don't load all pull requests attributes

* Fix typo

* wrong change copy head

* fix tests

* fix reactions

* Fix test

* fix fmt

* fix review comment reactions

* Migrate reactions when migrating repository from github

* fix missed sleep

* fix tests

* update reactions when external user binding

* Fix test

* fix tests

* change the copy head

* fix test

* fix migrator add/delete reaction

* Add require signed commit for protected branch

* Fix fmt

* Make editor show if they will be signed

* bugfix

* Add basic merge check and better information for CRUD

* linting comment

* Add descriptors to merge signing

* Slight refactor

* Slight improvement to appearances

* Handle Merge API

* manage CRUD API

* Move error to error.go

* Remove fix to delete.go

* prep for merge

* need to tolerate \r\n in message

* check protected branch before trying to load it

* Apply suggestions from code review

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

* fix commit-reader

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Add branch protection option to block merge on requested changes.

* Add migration step

* Fix check to correct negation

* Apply suggestions from code review

Language improvement.

Co-Authored-By: John Olheiser <42128690+jolheiser@users.noreply.github.com>

* Copyright year.

Co-authored-by: John Olheiser <42128690+jolheiser@users.noreply.github.com>
Co-authored-by: Lauris BH <lauris@nix.lv>

Add an option to protected branches to add writing deploy keys to the whitelist for pushing.

Please note this is technically a breaking change: previously if the owner of a repository was on the whitelist then any writing deploy key was effectively on the whitelist. This option will now need to be set if that is desired.

Closes #8472 

Details:
* Allow Protected Branches to Whitelist Deploy Keys
* Add migration
* Ensure that IsDeployKey is set to false on the http pushes
* add not null default false