TYP: type read_xml and deprecate passing positional arguments
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit) for how to run them
- [ ] whatsnew entry

cc @ParfaitG if any comments LGTM! Thanks, @phofl! cc @jreback can you rebase (as merged other one). or is this orthogonal? This should be orthogonal, but better to rebase thanks @phofl 