helix: prioritize environment packages

[noaccOS]

Description

packages in extraPackages are now the default packages helix can find, but specialized packages (eg from a devshell) are used if available

Checklist

• [ ] Change is backwards compatible.

• [X] Code formatted with ./format.

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

• [ ] Test cases updated/added. See example.

• [X] 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

@Philipp-M

[Philipp-M]

See also #5208.

@rycee, to avoid popping up the same change again, maybe just merge #5208?

[mrnossiom]

5208 has been merged. This is resolved.