Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/asyncio/runners.pyi

@@ -0,0 +1,10 @@
+import sys
+
+if sys.version_info >= (3, 7):
+    from typing import Awaitable, Optional, TypeVar
+
+    _T = TypeVar("_T")
+    if sys.version_info >= (3, 8):
+        def run(main: Awaitable[_T], *, debug: Optional[bool] = ...) -> _T: ...
+    else:
+        def run(main: Awaitable[_T], *, debug: bool = ...) -> _T: ...