Add modern "Accept", "Raise Concern" and "Resign" transactions to Audit
Ref T10978. This prepares for swapping the comment UI to stacked actions.
These are only accessible via the API.
Test Plan: Used the API to accept, raise concern with, and reject commits.
Reviewed By: chad
Maniphest Tasks: T10978
Differential Revision: https://secure.phabricator.com/D17182