Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/grp.pyi

@@ -0,0 +1,11 @@
+from typing import List, NamedTuple, Optional
+
+class struct_group(NamedTuple):
+    gr_name: str
+    gr_passwd: Optional[str]
+    gr_gid: int
+    gr_mem: List[str]
+
+def getgrall() -> List[struct_group]: ...
+def getgrgid(gid: int) -> struct_group: ...
+def getgrnam(name: str) -> struct_group: ...