Support reply controls

[mediaformat]

This plugin follows Wordpress site options, but a Post's comment options are not advertised in anyway.

The streams project uses commentPolicy with various options:

'commentPolicy' can be any of 'authenticated' - matches the typical ActivityPub permissions 'contacts' - matches approved followers 'any connections' - matches followers regardless of approval 'site: foobar.com' - matches any actor or clone instance from 'foobar.com' 'public' - matches anybody at all, may require moderation if the network isn't known 'self' - matches the activity author only 'until=2001-01-01T00:00Z' - comments are closed after the date given. This can be supplied on its own or appended to any other commentPolicy string by preceding with a space; for example 'contacts until=2001-01-01T00:00Z'.

We could minimally support until with get_option( 'close_comments_days_old' ) + post_publish date.

https://github.com/w3c/activitypub/issues/319 replyPreference https://github.com/mastodon/mastodon/issues/8565