Invite Only Communities

[Pdzly]

Have some invite only communities where moderators can only invite other people ( local only ? )

Idea:

For sensitive communities, private communities e.g. for a friends minecraft server to have a private community for news, tutorials, updates....

[Pdzly]

Depends on #342

[gaviscapes]

Having authorized fetch enforced would serve as a basis to securing this, but due to the nature of federation different quirks would still need to be accounted for as well.