jujutsu: fix config file location on Darwin

[Aehmlo]

Description

The jj tool loads its configuration from a platform-dependent location. On Darwin, it looks in ~/Library/Application Support/jj. This revision updates the programs.jujutsu module to serialize the generated configuration to the correct location.

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 system information:

$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"aarch64-darwin"`
 - host os: `Darwin 22.6.0, macOS 13.6.7`
 - multi-user?: `yes`
 - sandbox: `no`
 - version: `nix-env (Nix) 2.18.1`
 - channels(user): `""`
 - channels(root): `"nixpkgs-24.05"`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixpkgs`

• 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.

Maintainer CC

@shikanime

[huwaireb]

Looks like a duplicate of #5416.
cc @mrnossiom

[mrnossiom]

It seems to be, indeed. PR was blocked by obscure tests. Let me try to fix it right now with the info you provided.