Show a different invite screen if the invite is for an upgrade of a room we're already in

It can feel weird to receive an invite out of the blue for a room the user think they're already in. It would be nicer to instead show a different dialog making it more obvious that this is a room upgrade and not an invite to yet another room (especially since in this latter case it can very easily be misunderstood for scamming/phishing/impersonation).