Enable fp16 on CPU

[muellerzr]

What does this PR do?

This PR enables users to allow ops that can be done on CPU in FP16 to be done, without blocking them.

(Note: how well they work is TBD, at least the examples tests pass which have a threshold, but edge with caution)

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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• Did you write any new necessary tests?

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Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
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@amyeroberts @ydshieh

[amyeroberts]

Thanks!

Just a comment on a logic check

[amyeroberts]

Thanks!

[HuggingFaceDocBuilderDev]

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