WIP: ENH Add float[pyarrow] dtype
- Basing this off https://github.com/pandas-dev/pandas/pull/46972
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Hello @gsheni! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:













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

##### Comment last updated at 2022-05-15 03:47:56 UTC @github-actions pre-commit 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.