Support bridged rooms in a more friendly way

[turt2live]

Right now voyager just auto-joins the room, and some bridges may encounter issues with this.

Indirectly, this has been mentioned in vijfhoek/telematrix#18

If voyager joins the room it'll possibly cause permissions issues. This isn't unique to telematrix. The IRC bridge will create rooms if someone happens to link an alias, which is already happening (#freenode_#example:matrix.org is valid).

Unsure of how to handle this at the moment. Some way to query the bridge would probably work. #63 may help with this as bridged rooms should appear in the directory of the target server. Other options would be bridge-specific support for this kind of thing (ie: GET /api/room/#alias:domain.com results in {"exists":true}).

[14mRh4X0r]

Leaving a room when there are no or only appservice users might work as well, although I suppose you would need some kind of list of known appservices.

[Mikaela]

Are you aware of matrix-org/matrix-appservice-irc#1474 (comment) and able to either prove or disprove it? I think Voyager is on too many Libera.Chat bridged rooms and thus at times temporarily blocks new ones receiving messages from IRC when using the default room configuration.