Style: add type hints (#2217)

* style(routes): add_route argument, return typing

* style(listeners): typing

* style(views): typing as_view

* style(routes): change type hint

* style(listeners): change type hint

* style(routes): change type hint

* add some more types

* Change as_view typing

* Add some cleaner type annotations

Co-authored-by: Adam Hopkins <adam@amhopkins.com>

sanic/models/handler_types.py

@@ -21,5 +21,5 @@ MiddlewareType = Union[RequestMiddlewareType, ResponseMiddlewareType]
 ListenerType = Callable[
     [Sanic, AbstractEventLoop], Optional[Coroutine[Any, Any, None]]
 ]
-RouteHandler = Callable[..., Coroutine[Any, Any, HTTPResponse]]
+RouteHandler = Callable[..., Coroutine[Any, Any, Optional[HTTPResponse]]]
 SignalHandler = Callable[..., Coroutine[Any, Any, None]]