Metronome Complication (#303)

* Metronome Complication

A simple metronome complication that allows user to set BPM, toggle sound, and set counts per measure.

* silence warnings in metronome_face

* avoid mode button in metronome settings, other tweaks

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

movement/movement_faces.h

@@ -118,6 +118,7 @@
 #include "alarm_thermometer_face.h"
 #include "beeps_face.h"
 #include "accel_interrupt_count_face.h"
+#include "metronome_face.h"
 // New includes go above this line.
 
 #endif // MOVEMENT_FACES_H_