Deprecate `with_argparser_and_unknown_args` and add `with_unknown` parameter to `with_argparser`

[anselor]

Other than 2 lines, with_argparser_and_unknown_args is identical to with_argparser.

Suggest deprecating with_argparser_and_unknown_args and adding an optional parameter of with_argparser.

As a transitional near-term solution, we can just add the new parameter to with_argparser and change with_argparser_and_unknown_args to just call the common implementation.