Fix#14459
The following users can add/remove review requests of a PR
- the poster of the PR
- the owner or collaborators of the repository
- members with read permission on the pull requests unit
* Add repo type option to /api/repo/search
* Add tests and fix result of collaborative filter in specific condition
* Fix/optimize search & tests
* Improve integration tests
* Fix lint errors
* Fix unit tests
* Change and improve internal implementation of repo search
* Use NonexistentID
* Make search api more general
* Change mirror and fork search behaviour
* Fix tests & typo in comment