BUG: Allow passing of args/kwargs to groupby.apply with str func
- [x] closes #46479 (Replace xxxx with the Github issue number)
- [x] [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
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Precursor to #46072, where users doing `.groupby(...).apply("sum")` may get a warning that would not be able to be silenced without passing numeric_only.
thanks @rhshadrach 