Add show_flag_values in enum module. (#14928)

Author: guoci

stdlib/enum.pyi

@@ -309,6 +309,7 @@ if sys.version_info >= (3, 11):
     def global_enum(cls: _EnumerationT, update_str: bool = False) -> _EnumerationT: ...
     def global_enum_repr(self: Enum) -> str: ...
     def global_flag_repr(self: Flag) -> str: ...
+    def show_flag_values(value: int) -> list[int]: ...
 
 if sys.version_info >= (3, 12):
     # The body of the class is the same, but the base classes are different.