FR: reuse github token form /etc/nix/nix.conf

[ilyagr]

The reason I ran into #719 is that I reused the token from /etc/nix/nix.conf access-tokens option, where I have:

access-tokens = github.com=github_pat_ab<rest_of_token>

I think nh should be smart enough to use that token, or the one in ~/.config/nix/nix.conf if the user places it there. Perhaps this can fully replace nh's own token storage.

But, to be clear, this would be a nice-to-have and isn't as urgent as some fix to #719.

[faukah]

Good idea, but this should be explicitly opt-in. I don't want to silently read user's tokens. I'll add a configuration setting and an env var to do this.

[NotAShelf]

Good idea,

@atagen would be so proud of you rn