Convert ExtensionDtype class objects to instances of that class
- [x] closes #31356, closes #45417
- [ ] [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.

This enables behavior that would previously raise (and often confuse), e.g :

```python
pd.Series(["a", "b"], dtype=pd.StringDtype)
pd.api.types.is_bool_dtype(pd.BooleanDtype) == True
```
Ahh, thanks for the clarification. I must have misread https://github.com/pandas-dev/pandas/issues/45417#issuecomment-1014738149 to mean that the changes here were desirable.

Just to confirm (please correct as needed):

- Passing a class obj to `pandas_dtype`, `is_*_type`, etc. should always raise.
- https://github.com/pandas-dev/pandas/issues/45417 should be marked "it's a feature" and closed
- This PR should close https://github.com/pandas-dev/pandas/issues/31356 by raising a more informative message (with tests to confirm) yep that sounds right This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. Thanks for the pull request, but it appears to have gone stale. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen.