`negation-prefix` does not work with `short-option-groups`

[wdanilo]

Hi, I want to use short-option-groups and I want negation-prefix to work, however, yargs parses negation prefix only if it starts with --, so I can't use -no-window. Can this be improved, please? :)

[shadowspawn]

We would consider a pull request, but (sorry) I doubt the maintainers will work on this. short-option-groups is somewhat a historical setting and long options using a double-dash is the far more common pattern.