Use XDG standards for file locations

[cnf]

Currently, earlybird has a hardcoded path to the config file location. This just makes home dirs cluttered and messy.

We have freedesktop XDG Specfications on where to store data on a user system, and even various go packages to implement it.

I request earlybird to use proper freedesktop XDG specifications, but if the old path exists keep using it so we don't break user systems that already have an installation.

a quick explanation on XDG (not official)