Allow vm class to be given as positional argument to clone_vm

Create qube dialog uses it this way.

Fixess QubesOS/qubes-issues#9574

qubesadmin/app.py

@@ -359,7 +359,7 @@ def add_new_vm(self, cls, name, label, template=None, pool=None,
         self.domains.clear_cache()
         return self.domains[name]
 
-    def clone_vm(self, src_vm, new_name, *, new_cls=None, pool=None, pools=None,
+    def clone_vm(self, src_vm, new_name, new_cls=None, *, pool=None, pools=None,
                  ignore_errors=False, ignore_volumes=None,
                  ignore_devices=False):
         # pylint: disable=too-many-statements