feat(hardware): add gpu modules for intel/amd/nvidia

system/modules/hardware/gpu/default.nix

@@ -0,0 +1,19 @@
+{ lib, ... }:
+
+let
+  inherit (lib) types mkOption;
+in
+
+{
+  imports = [
+    ./amd
+    ./intel
+    ./nvidia
+  ];
+
+  options.systemModules.hardware.gpu.type = mkOption {
+    type = with types; nullOr (enum ["intel" "amd" "nvidia"]);
+    default = null;
+    description = "Type of gpu system module to use";
+  };
+}