go-freeze: Add module to configure package

[S0AndS0]

⚠️ This PR requires NixOS/nixpkgs#455648 to be accepted and flake.lock file here to be updated.

Description

This module allows for defining named configuration files via settings.<name> attributes, ex.

{
  programs.go-freeze = {
    enable = true;

    settings.user = {
      theme = "gruvbox-dark";
    };
  };
}

... which may be activated at runtime by name;

go-freeze -c user -l bash <<<'echo "hello world"';

Checklist

• Change is backwards compatible.

  Nope; requires NixOS/nixpkgs#455648 to be accepted and flake.lock file here to be updated

• Code formatted with nix fmt or
  nix-shell -p treefmt nixfmt deadnix keep-sorted --run treefmt.

• Code tested through nix run .#tests -- test-all or
  nix-shell --pure tests -A run.all.

  Note; check TODO in modules/programs/go-freeze.nix related to pkgs

• Test cases updated/added. See example.

• Commit messages are formatted like

  {component}: {description}
  
  {long description}
  

  See CONTRIBUTING for more information and recent commit messages for examples.

• If this PR adds a new module

  • Added myself as module maintainer. See example.
  • Generate a news entry. See News
  • Basic tests added. See Tests

• If this PR adds an exciting new feature or contains a breaking change.

  • Generate a news entry. See News