WIP: ENH Add float[pyarrow] dtype

[gsheni]

• Basing this off WIP: ENH Add int[pyarrow] dtype #46972
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

[pep8speaks]

Hello @gsheni! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2022-05-15 03:47:56 UTC

[gsheni]

@github-actions pre-commit

[mroeschke]

Thanks for starting this. Just a heads up, I think we won't be expanding support for pyarrow dtypes quite like this (the subclass approach).

If you'd like to help of this front, investigating how StringArrowArray and StringDtype for pyarrow can be further merged into ArrowExtensionArray and ArrowDtype respectively would be helpful instead.