feat: capture the config values being set by facter modules

[brianmcgee]

Adds two new config values:

• config.facter.debug.options which is a set of all option definitions where a facter module has affected its value e.g. is in the definitionsWithLocations list. This is useful for debugging which values are being set and what the resultant merged value ends up being.

• config.facter.debug.config which is a simpler breakdown of just the config values being applied by facter modules. It is taken from config.facter.debug.options and looks like this:

{
  boot = {
    initrd = {
      availableKernelModules = {
        "<facter>/modules/nixos/boot.nix" = [
          "uhci_hcd"
          "ata_piix"
          "virtio_pci"
          "virtio_blk"
        ];
        "<facter>/modules/nixos/virtualisation.nix" = [
          "virtio_net"
          "virtio_pci"
          "virtio_mmio"
          "virtio_blk"
          "virtio_scsi"
          "9p"
          "9pnet_virtio"
        ];
      };
      kernelModules = {
        "<facter>/modules/nixos/virtualisation.nix" = [
          "virtio_balloon"
          "virtio_console"
          "virtio_rng"
          "virtio_gpu"
        ];
      };
    };
    isContainer = { "<facter>/modules/nixos/virtualisation.nix" = false; };
    kernelModules = {
      "<facter>/modules/nixos/virtualisation.nix" = [ ];
    };
  };
  hardware = {
    parallels = {
      enable = { "<facter>/modules/nixos/virtualisation.nix" = false; };
    };
  };
  nixpkgs = {
    config = {
      "<facter>/modules/nixos/virtualisation.nix" = {
        allowUnfreePredicate = {
          _type = "if";
          condition = false;
          content = «lambda @ /nix/store/mdi0c47ynn0w0gvnwc3hnrszb22wd9hv-source/modules/nixos/virtualisation.nix:93:9»;
        };
      };
    };
    hostPlatform = {
      "<facter>/hosts/basic/config.nix" = "x86_64-linux";
      "<facter>/modules/nixos/system.nix" = "x86_64-linux";
    };
  };
  virtualisation = {
    hypervGuest = {
      enable = { "<facter>/modules/nixos/virtualisation.nix" = false; };
    };
    virtualbox = {
      guest = {
        enable = { "<facter>/modules/nixos/virtualisation.nix" = false; };
      };
    };
  };
}