use shellwords to split strings

[aawsome]

No description provided.

[simonsan]

Shell-words:
Last release is over a year ago on Feb 6, 2022.
PRs that are not merged are from August 2022: https://github.com/tmiasko/shell-words/pulls

Not sure if this change is needed?

[aawsome]

I came to shell_words by realizing that we already have it as dependency (in rustic, as dialoguer depends on it) and that it in fact solves the problem I tried to solve by the nom crate. It does so even better as the current solution doesn't support and handle \" in strings. So it is both an improvement and simplifies dependencies (a bit).
I'm open to exchange it with something else if there is a better choice! If not, I would just use it as the very popular dialoguer crate also uses it...