Added AMX acceleration

[johnbean393]

1. Added AMX acceleration to all 3 distance metrics using Apple's Accelerate framework.
2. Added Hashable and Identifiable conformance to SimilarityIndex

[ZachNagengast]

This is really cool thanks for the contribution! Do you have any sense of the speedup gain from these changes?

[johnbean393]

This is really cool thanks for the contribution! Do you have any sense of the speedup gain from these changes?

I was searching through a substantial index, and the time required went from 0.35 seconds to 0.05 seconds; so a 7x increase in speed. Note that since the new code uses hardware acceleration, the speed would differ on machines.

For context, the 7x increase in speed was recorded on my M2 Max MacBook, which has 2 AMX acceleration units. An A17 Pro would have only 1 of these AMX acceleration units, so expect only a ~3-4x increase in speed.

[ZachNagengast]

Good to merge! This should be a nice speedup 🙏