helm: init module

[folliehiyuki]

Description

This PR adds a new module programs.helm to install Helm package and manage Helm plugins.

Checklist

• Change is backwards compatible.

• Code formatted with ./format.

• Code tested through nix-shell --pure tests -A run.all or nix develop --ignore-environment .#all using Flakes.

• 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.

Maintainer CC

[teto]

before starting a review do you need this even when wrapHelm exists ?

[folliehiyuki]

I didn't know about wrapHelm. The wrapper approach overrides HELM_PLUGINS variable, pointing it to the Nix store, so it doesn't allow users to install a random Helm plugin with an one-off helm plugin install command.

With that said, I only use a few Helm plugins and they are all available in Nixpkgs. If no one desires the interactive CLI use case, I'll close this PR.

Thanks for the info btw!