Add __all__ to most modules beginning with 'n', 'o' and 'p' (#7345)

stdlib/os/path.pyi

@@ -2,5 +2,7 @@ import sys
 
 if sys.platform == "win32":
     from ntpath import *
+    from ntpath import __all__ as __all__
 else:
     from posixpath import *
+    from posixpath import __all__ as __all__