Generate programs.sqlite on nixpkgs branches

Currently, `programs.sqlite` database is only generated for the `nixos-` tarballs, and only for linux systems. This means that darwin systems lack proper command-not-found interface even though nothing is stopping it from having it if `nixpkgs-` tarballs also included `programs.sqlite` with a database for all 4 main systems (`{x86_64,aarch64}-{darwin,linux}`)