Add stock stopwatch face (#140)

Add stock stopwatch face (#140)

* buzzer sequences: first draft, does not work on hardware yet (but in simulator)

* buzzer sequences: add changes to movement.c

* buzzer sequences: add demo face to Makefile

* buzzer sequences: fix problem of interrupted sounds. Add logic for repeating sub sequences. Tidy up (move logic to watch_buzzer files, remove buzzer_demo_face)

* buzzer sequences: tidy up even more

* buzzer sequences: disable registering a 32 Hz tick callback for watch faces, so it will be used exclusively by the buzzer sequences functionality

* buzzer sequences: add callback slot functionality to watch_rtc and make watch_buzzer use it. Switch internal buzzer sequences tick frequency to 64 Hz. Revert changes to movement.c

* buzzer sequences: fix parameter sanity check in watch_rtc code

* stock stopwatch: first fully functional implementation

* stock stopwatch: fix typo in comment

* stock stopwatch: handle resuming from deep sleep mode properly

* buzzer sequences/watch_rtc: optimize calling tick callbacks in RTC_Handler

* buzzer sequences/watch_rtc: fix error in calling callback functions

* stock stopwatch: implement workaround for sleep mode

* stock stopwatch: merge current main into stock-stopwatch

* stock stopwatch: use TC counters as source for callbacks

* stock-stopwatch: revert unnecessary changes to watch_buzzer

Co-authored-by: joeycastillo <joeycastillo@utexas.edu>