Improve type of `MiddlewareType`

[guacs]

Is there an existing issue for this?

• [X] I have searched the existing issues

Is your feature request related to a problem? Please describe.

When using a custom Request class and type hinting the middleware with that custom Request class, type checkers complain that the argument types of the middleware function is invalid.

from sanic import Request, Sanic

class MyRequest(Request):
    ...

async def some_middleware(request: MyRequest) -> None:
    ...

app = Sanic("trial-app")

# This raises a type error.
app.register_middleware(some_middleware, "request")

# Pyright Error
# Argument of type "(request: MyRequest) -> Coroutine[Any, Any, None]" cannot be assigned to parameter
# "middleware" of type "MiddlewareType | Middleware" in function "register_middleware"
# Type "(request: MyRequest) -> Coroutine[Any, Any, None]" cannot be assigned to type "MiddlewareType | Middleware"
#  Type "(request: MyRequest) -> Coroutine[Any, Any, None]" cannot be assigned to type "RequestMiddlewareType"
#      Parameter 1: type "Request" cannot be assigned to type "MyRequest"
#        "Request" is incompatible with "MyRequest"
#    Type "(request: MyRequest) -> Coroutine[Any, Any, None]" cannot be assigned to type "ResponseMiddlewareType"
#      Function accepts too many positional parameters; expected 1 but received 2
#        Parameter 1: type "Request" cannot be assigned to type "MyRequest"
#          "Request" is incompatible with "MyRequest"

Describe the solution you'd like

Using a subclass of Request shouldn't raise this error by the type checkers.

Additional context

I think the fix is to make the Request type in MiddlewareType in handler_types a generic with the generic being bound to Request like it's done for the Sanic type.

[ahopkins]

Thanks. Do you think you can create the PR for this? 😎

[guacs]

Yeah I would love to. I'll get it ready in a day or two.