stdlib: Add many missing dunder overrides (#7231)

stdlib/unittest/mock.pyi

@@ -128,6 +128,8 @@ class NonCallableMock(Base, Any):
         **kwargs: Any,
     ) -> None: ...
     def __getattr__(self, name: str) -> Any: ...
+    def __delattr__(self, name: str) -> None: ...
+    def __setattr__(self, name: str, value: Any) -> None: ...
     if sys.version_info >= (3, 8):
         def _calls_repr(self, prefix: str = ...) -> str: ...
         def assert_called_with(self, *args: Any, **kwargs: Any) -> None: ...