IV-3 Only allow MusicBrainz tagged file on a pod

• forum : https://forum.funkwhale.audio/d/243-new-feature-only-allow-musicbrainz-tagged-file-to-be-uploaded
• spec : https://pad.funkwhale.audio/v5vPleb7SyK28B-4SjI7Hw
• mr : !2607 (merged)