Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/json/decoder.pyi

@@ -0,0 +1,29 @@
+from typing import Any, Callable, Dict, List, Optional, Tuple
+
+class JSONDecodeError(ValueError):
+    msg: str
+    doc: str
+    pos: int
+    lineno: int
+    colno: int
+    def __init__(self, msg: str, doc: str, pos: int) -> None: ...
+
+class JSONDecoder:
+    object_hook: Callable[[Dict[str, Any]], Any]
+    parse_float: Callable[[str], Any]
+    parse_int: Callable[[str], Any]
+    parse_constant: Callable[[str], Any] = ...
+    strict: bool
+    object_pairs_hook: Callable[[List[Tuple[str, Any]]], Any]
+    def __init__(
+        self,
+        *,
+        object_hook: Optional[Callable[[Dict[str, Any]], Any]] = ...,
+        parse_float: Optional[Callable[[str], Any]] = ...,
+        parse_int: Optional[Callable[[str], Any]] = ...,
+        parse_constant: Optional[Callable[[str], Any]] = ...,
+        strict: bool = ...,
+        object_pairs_hook: Optional[Callable[[List[Tuple[str, Any]]], Any]] = ...,
+    ) -> None: ...
+    def decode(self, s: str, _w: Callable[..., Any] = ...) -> Any: ...  # _w is undocumented
+    def raw_decode(self, s: str, idx: int = ...) -> Tuple[Any, int]: ...