BUG: Series.map may raise TypeError in Categorical or DatetimeTz
- [x] closes #12473
- [x] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [x] whatsnew entry

Needs to decide what categorical dtype `map` should return. Even though `apply` returns `object` dtype, but returning `category` is more consistent?
