AppOp::set_active_room_by_id: call set_state after changing the active room
Fixes GNOME/fractal#470
Unsent messages are set by set_state depending on the current active room so we need to set it before calling set_state.
Fixes GNOME/fractal#470
Unsent messages are set by set_state depending on the current active room so we need to set it before calling set_state.