Save wakeup alarms in non-volatile memory to preserve settings after device reset/watchdog reboot

[AndreySV]

Description

Sometimes devices reboots (by watchdog or because of low battery), then alarm time and settings are lost. As result alarm is missed and device has to be setup again to be used as wakeup source. This feature would be useful for regular repeatable alarms especially.

[minacode]

I would even label this as a bug.