ENH: Add engine keyword to expanding.apply to utilize Numba
- [x] closes #30936
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

actually ok for 1.0.0; can you add this issues / PR number to the whatsnew note that already existis for rolling.apply