Add cats.kernel.Hash-based CHAMP HashSet

[DavidGregory084]

This is a port of typelevel/cats#4185 to cats-collections.

[gemelen]

As I understand, it's a latest version from Cats PR, so it's already went through a review regarding code and performance. I have nothing to add to that review, as it's good to go from my point of view.

[armanbilge]

That's definitely the case for the HashMap, I think the HashSet (this PR) has had less direct review although I David did a great job applying review feedback from the HashMap also to the HashSet.

If the plans are for cats-collections to 1.0 in the near future (I hope so!) we should make sure everything is carefully reviewed :) I do think this one is in great shape!

[codecov-commenter]

Codecov Report

Merging #533 (9fc386e) into master (78f9e4f) will not change coverage. The diff coverage is n/a.

:exclamation: Current head 9fc386e differs from pull request most recent head aaa8a0a. Consider uploading reports for the commit aaa8a0a to get more accurate results

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##   master   #533   +/-   ##
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[DavidGregory084]

Is there anything more to be done here? Anything I can do to move this forward?