Update `Repository::ProjectPush` to implement `fabricate_via_api!`
The fabricate_via_api!
methods was implemented in Resource::MergeRequest
in !14336 (merged), but it depends on Repository::ProjectPush
, which does not implement fabricate_via_api!
.
fabricate_via_api!
should be implemented in Repository::ProjectPush
so that Resource::MergeRequest.fabricate_via_api!
doesn't use the UI.