Re-organize directory structure (#4971)

See discussion in #2491

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

stubs/toml/METADATA.toml

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

stubs/toml/toml.pyi

@@ -0,0 +1,19 @@
+import sys
+from _typeshed import StrPath, SupportsWrite
+from typing import IO, Any, List, Mapping, MutableMapping, Text, Type, Union
+
+if sys.version_info >= (3, 6):
+    _PathLike = StrPath
+elif sys.version_info >= (3, 4):
+    import pathlib
+
+    _PathLike = Union[StrPath, pathlib.PurePath]
+else:
+    _PathLike = StrPath
+
+class TomlDecodeError(Exception): ...
+
+def load(f: Union[_PathLike, List[Text], IO[str]], _dict: Type[MutableMapping[str, Any]] = ...) -> MutableMapping[str, Any]: ...
+def loads(s: Text, _dict: Type[MutableMapping[str, Any]] = ...) -> MutableMapping[str, Any]: ...
+def dump(o: Mapping[str, Any], f: SupportsWrite[str]) -> str: ...
+def dumps(o: Mapping[str, Any]) -> str: ...