Handle positional arguments starting with a sigle or double dash

[janvhs]

It's a common pattern to be able to input positional arguments with leading hyphens after having specified -- once.
An as an example printf "%s\n" "-pos" | grep -i -- -pos. This is a test I just wrote describing this behaviour

[janvhs]

I was in the progress of adding this, but ended up doing infra instead

[natemoo-re]

Thanks for the test! Even if you just open a PR with the failing test and don't have time to implement the feature, that's still helpful 👍

[janvhs]

Sure, I'm going to spend some time implementing it during this Sunday afternoon (German time), otherwise I'll just PR some tests describing the behaviour :D