Add CLI

[alexarchambault]

I think it'd be nice / convenient if directories-jvm had a CLI, to print the directories of an app, from its name, on the current OS. It could be used like

$ directories coursier --cache-dir
/Users/alex/Library/Caches/Coursier

[alexarchambault]

@soc If you're ok with the idea, I can give it a try if you'd like.

[soc]

@alexarchambault Could we do this as a separate module?

Such that people who only need the library can use it without dragging in CLI/parsing code? (Maybe named directories-jvm-cli or something?)

[alexarchambault]

Could we do this as a separate module?

Yes, that's what I was thinking about.

I'm thinking about maybe using picocli to parse arguments, or parsing them manually if picocli ends up not doing the job.