Conform to XDG spec please

The XDG Base Directory Specification is not some new thing, it's been around for a while. Writing a new project? Use it. Updating an old project? Use it. It's not hard to implement, it's not hard to use. Don't just throw a .<app> to user home directory, or be like ~/go.

• HackerNews Discussion (2023-03)
• Use the XDG Base Directory Specification! (@hyperupcall)
• XDG-Ninja(@b3nj5m1n)

It should be very easy to implement even without a library. But if you are lazy:

• Deno/Node Implementation (@srstevenson)
• Go Implementation (@adrg)
• Rust Implementation (@whitequark)