build-inventory: move inventory and inventoryClass into explizitly different folders

lib/modules/inventoryClass/inventory-introspection.nix

@@ -0,0 +1,16 @@
+{
+  config,
+  lib,
+  clanLib,
+  ...
+}:
+{
+  options.introspection = lib.mkOption {
+    readOnly = true;
+    # TODO: use options.inventory instead of the evaluate config attribute
+    default =
+      builtins.removeAttrs (clanLib.introspection.getPrios { options = config.inventory.options; })
+        # tags are freeformType which is not supported yet.
+        [ "tags" ];
+  };
+}