Note : this is a copy of #21385 but on the right branch.

Motivation for this change

Make os-prober available on nixos, and eventually solve #7406
With this package, I can use os-prober this way :

  boot.loader.grub = {
    enable = true;
    version = 2;
    device = "/dev/sda";
    extraPrepareConfig = "PATH=$PATH:${pkgs.os-prober}/bin:${pkgs.busybox}/bin pkgdatadir=${pkgs.grub2}/share/grub ${pkgs.grub2}/etc/grub.d/30_os-prober > /boot/grub/grub-os-prober.cfg";
    extraEntries = ''
      menuentry 'Other OS' {
        configfile $prefix/grub-os-prober.cfg
      }
    '';
  };

Still not perfect, but at least it works.

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.