at the moment, to set status of PipelineRun on GitLab MR we commit status API of GitLab which has limitation e.g. if MR is raised by an unauthorized user from an fork of the upstream, using commit status api it is not possible to update the status due to authorization issue. to solve the issue there is an API introduced by GitLab External status https://docs.gitlab.com/user/project/merge_requests/status_checks/. this story tracks the experiment with that API if that works for PaC or not.