DEPR: Add deprecation warning for factorize() order keyword
#### What's this PR do?
In response to #19727.
Adds functionality to the ``deprecate_kwargs`` utility.  Currently, the utility doesn't allow the deprecation of an old keyword without having a new one in place.  The change proposed here allows the deprecation of an *old* keyword without specifying a *new* keyword by allowing users to pass ``new_arg_name=None``  to ``deprecate_kwargs``. 

#### PR checklist
- [X] closes #19727
- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] whatsnew entry
