vars: reduce dependency on pkgs

pass pkgs only to generators submodule which is the only place where it is needed because of finalScript

nixosModules/clanCore/vars/interface.nix

@@ -27,6 +27,12 @@ let
     ;
   # the original types.submodule has strange behavior
   submodule =
+    module:
+    submoduleWith {
+      modules = [ module ];
+    };
+
+  submoduleWithPkgs =
     module:
     submoduleWith {
       specialArgs.pkgs = pkgs;
@@ -44,7 +50,7 @@ in
       '';
       default = { };
       type = attrsOf (
-        submodule (generator: {
+        submoduleWithPkgs (generator: {
           imports = [ ./generator.nix ];
           options = {
             name = lib.mkOption {