Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/_tracemalloc.pyi

@@ -0,0 +1,17 @@
+import sys
+from tracemalloc import _FrameTupleT, _TraceTupleT
+from typing import Optional, Sequence, Tuple
+
+def _get_object_traceback(__obj: object) -> Optional[Sequence[_FrameTupleT]]: ...
+def _get_traces() -> Sequence[_TraceTupleT]: ...
+def clear_traces() -> None: ...
+def get_traceback_limit() -> int: ...
+def get_traced_memory() -> Tuple[int, int]: ...
+def get_tracemalloc_memory() -> int: ...
+def is_tracing() -> bool: ...
+
+if sys.version_info >= (3, 9):
+    def reset_peak() -> None: ...
+
+def start(__nframe: int = ...) -> None: ...
+def stop() -> None: ...