power,media-keys: Signal connector rather than output ID
This is intended for stable too. The changes are not tested yet (need a bit after having upgraded to F30).
We don't have the concept of an output ID anymore in the DBus API. The current code was entirely broken for a long time now (i.e. never signalled any output) and the fixup for 3.32 that I did was actually doing guesses that were incorrect.
Fix this properly by passing around the connector name rather than an output ID. This requires changes in gnome-shell to work properly (but doesn't regress without those changes).
Fixes: #401 (closed)