Add room state type to define formatting rules per room

[Half-Shot]

The plan here would be a org.matrix.matrix-appservice-irc.room_configuration event which would be used to define formats for pastebinning, mentions, replies, edits etc so that admins of the room could configure their own criteria for how messages should be formatted with the bridge config providing it's own defaults.

This would likely solve some off the standoffs we have for formatting in #1179

[Midar]

How would this work for dynamically created rooms? E.g. I might be the only Matrix users in a room and might want to configure it, but am not an OP on the IRC side. It seems like this is something that should be configured per user rather than per room.

[DataDrake]

Why not just check for +c in the channel mode and act accordingly?