Add CLI flag to ignore hidden directories and/or support .gitignore

[ahgraber]

I have "work in progress" .wip/ directories in my local repo that are included in my .gitignore. As these are work in progress, they may be in a state that cause flux-local to crash.

It would be really useful to be able to set flux-local (and the gh Action) to ignore directories that:

• in the .gitignore
• match a glob/regex pattern