Add type hints - beef up docstrings - test examples, etc.

[jGaboardi]

This turned into a rather PR and I can split for ease of review, if desired.

• resolves add type hints #55
• resolves beef up docstrings #56
• resolves add a descriptive __repr__() to FastPair #67
• resolves perform type testing with mypy #70
• resolves typing.Self only available in Python 3.11+ #73
• resolves add pytest-doctestplus for doctest-only option #74
• resolves test against both intel & apple silicon -- macOS CI #75

cc @gegen07

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All modified and coverable lines are covered by tests ✅

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Additional details and impacted files

@@           Coverage Diff           @@
##             main      #72   +/-   ##
=======================================
  Coverage   100.0%   100.0%           
=======================================
  Files           2        3    +1     
  Lines         125      154   +29     
=======================================
+ Hits          125      154   +29     

Files	Coverage Δ
fastpair/base.py	100.0% <100.0%> (ø)
fastpair/types.py	100.0% <100.0%> (ø)

[jGaboardi]

While I do think think that all the declared typing in L16-52 is verbose, it was a great way to learn the data structure better and has already helped with identifying ways to potentially improve the codebase (#69). If we are on the fence at all about keeping them, I'm in very favor of it.

Also, maybe we want to plop them into another file, e.g. fp_typing.py or something?

[gegen07]

+1 to create another file to typing.

[jGaboardi]

@gegen07 -> typing broken out in types.py