Re-organize directory structure (#4971)

See discussion in #2491

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

stubs/atomicwrites/METADATA.toml

@@ -0,0 +1,2 @@
+version = "0.1"
+python2 = true

stubs/atomicwrites/atomicwrites/__init__.pyi

@@ -0,0 +1,16 @@
+from _typeshed import AnyPath
+from typing import IO, Any, AnyStr, Callable, ContextManager, Optional, Text, Type
+
+def replace_atomic(src: AnyStr, dst: AnyStr) -> None: ...
+def move_atomic(src: AnyStr, dst: AnyStr) -> None: ...
+
+class AtomicWriter(object):
+    def __init__(self, path: AnyPath, mode: Text = ..., overwrite: bool = ...) -> None: ...
+    def open(self) -> ContextManager[IO[Any]]: ...
+    def _open(self, get_fileobject: Callable[..., IO[AnyStr]]) -> ContextManager[IO[AnyStr]]: ...
+    def get_fileobject(self, dir: Optional[AnyPath] = ..., **kwargs: Any) -> IO[Any]: ...
+    def sync(self, f: IO[Any]) -> None: ...
+    def commit(self, f: IO[Any]) -> None: ...
+    def rollback(self, f: IO[Any]) -> None: ...
+
+def atomic_write(path: AnyPath, writer_cls: Type[AtomicWriter] = ..., **cls_kwargs: object) -> ContextManager[IO[Any]]: ...