* api: set the job submission during job reversion
This PR fixes a bug where the job submission would always be nil when
a job goes through a reversion to a previous version. Basically we need
to detect when this happens, lookup the submission of the job version
being reverted to, and set that as the submission of the new job being
created.
* e2e: add e2e test for job submissions during reversion
This e2e test ensures a reverted job inherits the job submission
associated with the version of the job being reverted to.
