Settings for ItemSegment creation rules about locokit

[sobri909]

Hm. Actually it might make more sense to do something like this:

// segments groups by matching activityType and recordingState
let segmentsByType = item.segments(groupedBy: [\.activityType, \.recordingState])

Otherwise I'll end up having to hardcode a computed property for every combination that seems useful, and in the process will fail to provide combinations that might be useful but that I didn't expect.

This approach could allow all sorts of useful groupings, for example:

// segments groups by matching activityType and stepHz
let segmentsByTypeAndCadence = item.segments(groupedBy: [\.activityType, \.stepHz])`

That would allow for doing cool things like easily identifying the "sprinting" segments of running and cycling paths.

[sobri909]

I've done the stopgap solution for v6.0, so will bump this cooler, more complex solution to the v6.1 milestone.