FIX: fix interpolate with kwarg limit area and limit direction using pad or bfill
- [x] closes #26796
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

This separates a large part of the code changes from #25141 to keep things comprehendible.
