Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/macurl2path.pyi

@@ -0,0 +1,7 @@
+import sys
+from typing import Union
+
+if sys.version_info < (3, 7):
+    def url2pathname(pathname: str) -> str: ...
+    def pathname2url(pathname: str) -> str: ...
+    def _pncomp2url(component: Union[str, bytes]) -> str: ...