Co-authored-by: Claire <claire.github-309c@sitedethib.com>

Co-authored-by: Liam Cooke <liam@liamcooke.com>
Co-authored-by: John Holdun <john@johnholdun.com>
Co-authored-by: Effy Elden <effy@effy.space>
Co-authored-by: Lina Reyne <git@lina.pizza>
Co-authored-by: Lina <20880695+necropolina@users.noreply.github.com>
Co-authored-by: Claire <claire.github-309c@sitedethib.com>

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

Co-authored-by: Jean Boussier <jean.boussier@gmail.com>

* Validate internal actor

* Use “internal.actor” by default for the server actor username

* Fix instance actor username on the fly if it includes ':'

* Change actor name from internal.actor to mastodon.internal

* Fix BackfillAdminActionLogs post-deployment migration

* Improve migration tests

* Backfill admin action logs again

* Add tests

* Fix crash when trying to display orphaned action logs

* Add migration for older admin action logs