cleanup redundant param in Route initialization

[laggardkernel]

Param "before_request" is never passed to Route.__init__(). Or say it in another way, a "before_request" function is never converted to a Route instance. It's saved to Router.before_requests during route registration.

class Router:
    def add_route(...):
        if before_request:
            if websocket:
                self.before_requests.setdefault("ws", []).append(endpoint)
            else:
                self.before_requests.setdefault("http", []).append(endpoint)
            return
        # before request function is saved into `Router.before_requests` dict,
        # never be passed into `Route`, or `WebsocketRoute`