Lock down kwargs in offsets signatures
Explicitly specify allowed kwargs in `__init__` for `Week`, `WeekOfMonth`, `LastWeekOfMonth` and `QuarterOffset`.

Ref #17176 

Intended to be orthogonal/complementary to #17450.

Will add tests after confirming we're on the same page.

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry
