fractal-matrix-api: set history visibility for direct chats
requested to merge BrainBlasted/fractal:wip/christopherdavis/change-direct-chat-visibility into master
We didn't specify the visibility for participants in direct chats. The default behavior when unspecified is confusing, and leads to messages sent between the sending of an invite and the acceptance of it being dropped.
Now we append a state event to our room creation that sets the room visibility to "invited", meaning users can see messages from when they were invited.