Add typing to unittest.mock._patch_dict.__call__ (#16310)

* Add overloads to `unittest.mock._patch_dict.__call__`

* Simplify _patch_dict.__call__ to single overload

_F's bound (Callable[..., Any]) already covers the class and async
cases, and generic solving binds to the actual argument type rather
than the bound, so the separate _TT/_AF overloads were redundant.

Author: mxr

stdlib/unittest/mock.pyi

@@ -301,7 +301,7 @@ class _patch_dict:
     values: Any
     clear: Any
     def __init__(self, in_dict: Any, values: Any = (), clear: Any = False, **kwargs: Any) -> None: ...
-    def __call__(self, f: Any) -> Any: ...
+    def __call__(self, f: _F) -> _F: ...
     def __enter__(self) -> Any: ...
     def __exit__(self, *args: object) -> Any: ...
     def decorate_callable(self, f: _F) -> _F: ...