Improve MotorController flexibility

[mark9064]

Refactors motor controller to:

• Support ringing any number of times, with any period between rings
• Adaptively change the vibration strength based on how much the watch is moving
• Use predefined strength values (light/medium/strong) rather than arbitrary numbers across the codebase

Other changes:

• Chime is now implemented as 2 rings 200ms apart. This sets it nicely apart from normal notifications

Internal changes:

• Only one timer is used for ringing
• State machine (Idle, Buzz, RingOn (ringing with motor on), RingOff (ringing with motor off))

Would be interested to hear what people make of the adaptive vibration strength. I think it's definitely led to me missing fewer notifications when on the move

[github-actions]

Build checks have not completed. Possible reasons for this are:

1. The checks need to be approved by a maintainer
2. The branch has conflicts
3. The firmware build has failed

[mark9064]

10.3 is too stupid to build this apparently...