Open source Arc App's HealthKit hooks

[sobri909]

Arc App has various extensions in its TimelineItem subclasses for fetching data from HealthKit. There's no reason why these can't be moved to LocoKit.

They should be wrapped in HealthKit module availability tests. But otherwise they should mostly be easily moved upstream from Arc App's ArcPath and ArcVisit subclasses and into the main Path and Visit classes. (Or more likely directly into the base TimelineItem class, given that they currently live in an ArcTimelineItem protocol).

Would probably also need to move over Arc App's HealthKit wrapper class, for simplified data fetching.

HKQuantityTypes

• stepCount
• activeEnergyBurned
• heartRate (average value for the timeline item, and max value for the timeline item)

HKObjectTypes

• sleepAnalysis
• workoutType

It should also be easily extensible to support fetching of more HK types in custom subclasses, etc.