Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/getpass.pyi

@@ -0,0 +1,6 @@
+from typing import Optional, TextIO
+
+def getpass(prompt: str = ..., stream: Optional[TextIO] = ...) -> str: ...
+def getuser() -> str: ...
+
+class GetPassWarning(UserWarning): ...