Depends on D20580. Fixes T13311. When we choose which actions to show a user, we can either show them "auditor" actions (like "raise concern") or "author" actions (like "request verification").
Currently, we don't show "author" actions if you're the author of the commit via an identity mapping, but we should. Use identity mappings where they exist.
(Because I've implemented getEffectiveAuthorPHID() in a way that requires $data be attached, it's possible this will make something throw a "DataNotAttached" exception, but: probably it won't?; and that's easy to fix if it happens.)