ENH: Add to_latex() method to Series (#16180)
This changeset adds _repr_latex_ to the Series class and moves
the to_latex() method from the DataFrame class to the NDFrame
class.

 - [ ] closes #16180
 - [ ] tests added / passed
 - [ ] passes ``git diff upstream/master --name-only -- '*.py' | flake8 --diff``
 - [ ] whatsnew entry
