Support vibration notification in Alarm

I didn't see an issue for this but thought we should track it. An alarm using the vibration motor would be a very effective alert even in the case where the user left headphones plugged in/associated or otherwise sound was disabled (muted phone in your pocket).

It appears it would require a change here to use libfeedback APIs: https://source.puri.sm/Librem5/gnome-clocks/blob/librem5-3-32/src/utils.vala#L327