devicenotifications: Play notification also for output devices
This is going directly through kde_output_device_v2 since we want it as direct user feedback that the cable is plugged in, even if the output is not configured or turned off. QScreen is only active outputs.
Compress add/remove events
In case multiple devices show up or disappear in quick succession, such as when plugging in/out a docking station.
Superseds kwin!4283 (closed) and keeps it out of KWin and together with rest of device notifications
Edited by Kai Uwe Broulik