Move AddCollabrator and CreateRepositoryByExample to service layer (#32419)

- [x] Move `CreateRepositoryByExample` to service layer
- [x] Move `AddCollabrator` to service layer
- [x] Add a new parameter for `AddCollabrator` so that changing mode
immediately after that will become unnecessary.

routers/api/v1/api.go

@@ -1172,7 +1172,7 @@ func Routes() *web.Router {
 					m.Get("", reqAnyRepoReader(), repo.ListCollaborators)
 					m.Group("/{collaborator}", func() {
 						m.Combo("").Get(reqAnyRepoReader(), repo.IsCollaborator).
-							Put(reqAdmin(), bind(api.AddCollaboratorOption{}), repo.AddCollaborator).
+							Put(reqAdmin(), bind(api.AddCollaboratorOption{}), repo.AddOrUpdateCollaborator).
 							Delete(reqAdmin(), repo.DeleteCollaborator)
 						m.Get("/permission", repo.GetRepoPermissions)
 					})