Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/_compression.pyi

@@ -0,0 +1,23 @@
+from _typeshed import WriteableBuffer
+from io import BufferedIOBase, RawIOBase
+from typing import Any, Callable, Tuple, Type, Union
+
+BUFFER_SIZE: Any
+
+class BaseStream(BufferedIOBase): ...
+
+class DecompressReader(RawIOBase):
+    def __init__(
+        self,
+        fp: RawIOBase,
+        decomp_factory: Callable[..., object],
+        trailing_error: Union[Type[Exception], Tuple[Type[Exception], ...]] = ...,
+        **decomp_args: Any,
+    ) -> None: ...
+    def readable(self) -> bool: ...
+    def close(self) -> None: ...
+    def seekable(self) -> bool: ...
+    def readinto(self, b: WriteableBuffer) -> int: ...
+    def read(self, size: int = ...) -> bytes: ...
+    def seek(self, offset: int, whence: int = ...) -> int: ...
+    def tell(self) -> int: ...