refactor(systemModules): move hardware --> device/hardware, add function option

system/modules/device/hardware/features/default.nix

@@ -0,0 +1,19 @@
+{ lib, config, ... }:
+
+let
+  inherit (lib) types mkOption;
+in
+
+{
+  imports = [
+    ./bluetooth
+    ./backlight
+    ./battery
+  ];
+
+  options.systemModules.hardware.features = mkOption {
+    type = with types; listOf (enum ["bluetooth" "backlight" "battery"]);
+    default = [];
+    description = "What extra hardware feature system modules to use";
+  };
+}