XDG_CONFIG_HOME support

[ptman]

Is your feature request related to a problem? Please describe.
You seem to have some support for XDG directories, but still litter my $HOME. Please put config files in $XDG_CONFIG_HOME. Add a command to fire up an editor on the config file if you must.

Describe the solution you'd like
~/.config/fleek/fleek.yaml

Describe alternatives you've considered
symlinks, wrapper script to temporarily set another $HOME

[jcrben]

It would also be better to move config directories out of ~/local/fleek/user.nix - that's more XDG_DATA_HOME