Show delete and undelete events in submission activity feed

[matthew-white]

If a submission is deleted, then undeleted, it'd be useful to include those events in the activity feed on the submission details page. Seeing those events will make the history clear, including the time period when the submission was not available for most functions.

The submission details page will initially be the only place where we surface these events. They won't be shown on the server audit log page, since we don't show events about individual submissions or entities there. Maybe at some point there will be another audit log (e.g., for the individual project) where we would also surface these events.