Add type hints for orjson (#2747)

third_party/3/orjson.pyi

@@ -0,0 +1,14 @@
+# https://github.com/ijl/orjson/blob/master/orjson.pyi
+
+from typing import Any, Callable, Optional, Union
+
+def dumps(
+    obj: Any, default: Optional[Callable[[Any], Any]], option: Optional[int]
+) -> bytes: ...
+def loads(obj: Union[bytes, str]) -> Any: ...
+
+class JSONDecodeError(ValueError): ...
+class JSONEncodeError(TypeError): ...
+
+OPT_STRICT_INTEGER: int
+OPT_NAIVE_UTC: int