[#1505] Threads / replies federation
Adds support for ActivityStreams replies
collection for outgoing federation and background fetching of incoming notes' replies
collection items (implementation mimics Mastodon implementation: [:activitypub, :note_replies_output_limit]
defaults to 5, only self-replies are included in replies
collection).
Adds background fetching of replies
collection items.
Closes #1505 (closed)