Use XDG Base Directory Spec for locating config files instead of current dir

[samlaf]

Is your feature request related to a problem? Please describe.

Right now devnet init creates a devnet.yaml file in the current directory, which is not very ideal since:

1. I should be able to use the cli irrespective of my current directory
2. This would lead to clutter all over my filesystem if I am not careful

Describe the solution you'd like

I would recommend using https://specifications.freedesktop.org/basedir-spec/latest/index.html which is a standard to place config/cache/data for different apps/clis.

$XDG_CONFIG_HOME/yourapp/config.yaml  (defaults to ~/.config/yourapp/)
$XDG_DATA_HOME/yourapp/              (defaults to ~/.local/share/yourapp/)
$XDG_CACHE_HOME/yourapp/             (defaults to ~/.cache/yourapp/)

There's even a golang package available to deal with this spec: https://github.com/adrg/xdg

Describe alternatives you've considered

Additional context

[MegaRedHand]

We expect projects to commit these config files to their repositories, like Makefiles, Dockerfiles, or plain bash scripts (configuration might be a misnomer since they are more like specifications). Storing them inside a devnet config dir would make this more difficult for users.

This info is undoubtedly useful, though. Thanks for sharing!

[samlaf]

@MegaRedHand i see that makes sense! Would be valuable info to add to the top of the readme I feel. Point to a repo example that was built with the CLI, and add “init” steps to create a new one with best practice recommendations.