Feat: Watch/Radio Alarm Face

[chgio]

This adds a new complication-type watchface with the following features:

• AM/PM/AM&PM alarm period selection for merchant-navy bridge/engine watches;
• hour/half-hour/quarter-hour beep period selection for marine radio silence or reporting duties.

I realise the similarities with the Advanced Alarm and the legacy Ship's Bell faces, but I believe this one sits in a "middle-ground" between the two, providing basic recurring alarms and bell chimes out of a single face.

Display

Legend:

1. Alarm time (hh:MM)
2. Alarm period: none (AM) / PM (PM) / 24H (AM&PM)
3. Chime period: 60/30/15 (minutes)
4. Alarm & Chime state: on/off each

Operation

Largely just like the standard alarm:

• Starts in normal mode, where every press of the Alarm button cycles through alarm/chime state combinations:
  • Both off
  • Chime on
  • Alarm on
  • Both on
• A long press of the Alarm button enters setting mode, where every press of the Light button cycles through fields to set:
  • Alarm hh (wraps around after 11)
  • Alarm MM
  • Alarm period ("LAP" indicator blinks, alarm autoset to on upon selection)
  • Chime period (chime autoset to on upon selection)

Notes

The chime on/off state doesn't show up on the clock face.

This is because the clock face's WATCH_INDICATOR_BELL can only be set by itself, as it handles toggling the hourly chime internally -- unlike for WATCH_INDICATOR_SIGNAL, which can be set externally through movement_set_alarm_enabled(). I'm planning to extend the same interface to the chime too (chgio#3), and will share a PR when it's ready.

In the meantime, I appreciate any feedback on this matter and on the watchface in general.