EVENT_ALARM_BUTTON_UP doesn't always fire on watch wakeup

[neutralinsomniac]

If you hit the alarm button really fast to wake the watch up, the EVENT_ALARM_BUTTON_UP event won't fire.

From @josecastillo:
"when the watch is in low energy mode, the external interrupt controller isn't running, and the alarm pin is assigned to the RTC's external wake function. when that external wake happens, Movement has to re-enable the EIC and reassign that pin from the RTC to the EIC. and i'm seeing that it doesn't do that straight away, there's an unnecessary interaction with the (relatively slow) RTC peripheral happening first"