See #689 (closed)
This MR implement the federation part for metadata update:
- Broadcasting applied edits to federation (via an
Updateactivity) - Receiving and handling those updates
- Verifying that the update comes either from the service actor or the actor referenced in the
attributedTofield of the updated entity
This requests also restore some tests that were previously deleted in federation/tests_serializers.py
Cf https://mastodon.eliotberriot.com/@eliotberriot/101902286936717693