Added --print-path flag to print common paths

[mitsuhiko]

I was trying to debug why stuff was not loading on my windows machine and learned in the process that the paths are quite different. Since I was trying to rewrite the config file for a test automatically I needed to add platform specific logic. That might be something people need to do more commonly so this adds a --print-path argument that can be used for scripting.

Example:

$ hx --print-path config-file
/Users/mitsuhiko/.config/helix/config.toml

Feel free to close this down. This seems valuable to me, but it might be too specific.

[the-mikedavis]

These should be printed by hx --health and not add a new flag

[mitsuhiko]

My use for this was external scripting. Parsing the output of hx --health seems brittle.

[pascalkuthe]

I am closing this one out as stale. We want to keep the command line very minimal. These days health prints most of these flags. I don't see us adding a dedicated flag. Thank you for contributing!