Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/runpy.pyi

@@ -0,0 +1,22 @@
+from types import ModuleType
+from typing import Any, Dict, Optional, TypeVar
+
+_T = TypeVar("_T")
+
+class _TempModule:
+    mod_name: str = ...
+    module: ModuleType = ...
+    def __init__(self, mod_name: str) -> None: ...
+    def __enter__(self: _T) -> _T: ...
+    def __exit__(self, *args: Any) -> None: ...
+
+class _ModifiedArgv0:
+    value: Any = ...
+    def __init__(self, value: Any) -> None: ...
+    def __enter__(self: _T) -> _T: ...
+    def __exit__(self, *args: Any) -> None: ...
+
+def run_module(
+    mod_name: str, init_globals: Optional[Dict[str, Any]] = ..., run_name: Optional[str] = ..., alter_sys: bool = ...
+) -> Dict[str, Any]: ...
+def run_path(path_name: str, init_globals: Optional[Dict[str, Any]] = ..., run_name: str = ...) -> Dict[str, Any]: ...