Add push to remote mirror repository (#15157)

Add push to remote mirror repository (#15157)

* Added push mirror model.

* Integrated push mirror into queue.

* Moved methods into own file.

* Added basic implementation.

* Mirror wiki too.

* Removed duplicated method.

* Get url for different remotes.

* Added migration.

* Unified remote url access.

* Add/Remove push mirror remotes.

* Prevent hangs with missing credentials.

* Moved code between files.

* Changed sanitizer interface.

* Added push mirror backend methods.

* Only update the mirror remote.

* Limit refs on push.

* Added UI part.

* Added missing table.

* Delete mirror if repository gets removed.

* Changed signature. Handle object errors.

* Added upload method.

* Added "upload" unit tests.

* Added transfer adapter unit tests.

* Send correct headers.

* Added pushing of LFS objects.

* Added more logging.

* Simpler body handling.

* Process files in batches to reduce HTTP calls.

* Added created timestamp.

* Fixed invalid column name.

* Changed name to prevent xorm auto setting.

* Remove table header im empty.

* Strip exit code from error message.

* Added docs page about mirroring.

* Fixed date.

* Fixed merge errors.

* Moved test to integrations.

* Added push mirror test.

* Added test.