feat(mod): utilize ~/.gno dir

[harry-hov]

Related: #462

See discussion: #479 (comment)

[thehowl]

Mhhh. I personally dislike it when software create a new directory in my $HOME. I would rather they used ~/.local/share/ or ~/.cache.

I don't know if this conversation was already had previously, but if we're extending the use of GNO_HOME, I think we should consider having it elsewhere?

[moul]

What about following other standards such as the XDG_ and other well-known environment variables, in order to adhere to best practices on various systems and allow users to override the default value if desired?

[moul]

This PR does not involve creating a new folder, but rather reusing the existing one that is created and used globally for gno.

Let's take a closer look at @harry-hov's work for this addition which is finally more as a merge + making gno more independent from go in terms of FS (which is good IMO). Then reevaluate if we should pursue a different approach for managing config-dirs globally. @thehowl, what are your thoughts on my previous comment?

[moul]

LGTM for the PR

We would like to ensure that @thehowl's valid concern is addressed before merging, for example, by inserting or updating issues.

[thehowl]

@moul Created #655 for that