fish: also query pname and version for completions

[a-kenji]

Description

Query the pname and version attributes for completion generation, if the name attribute is not available.

Fixes #2813

This is pretty much @stopbystudent's approach from the issue.
I tried using pkgs.lib.getName, but didn't find a good way to integrate it.

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

I couldn't find a meta.maintainers, so:

$ git log --since='2023-01-01' --follow --format='%an <%ae>' -- modules/programs/fish.nix | sort | uniq

@emilazy
@yu-re-ka
@marsam

[rycee]

Thanks! I don't know much about fish but this looks reasonable to me so I merged to master now 🙂