fix: update grpc_web_server.dart envoy config to support newer envoy version (#760)

Co-authored-by: Moritz <[email protected]>

Author: aran

test/grpc_web_server.dart

@@ -81,8 +81,14 @@ static_resources:
                 expose_headers: custom-header-1,grpc-status,grpc-message
           http_filters:
           - name: envoy.filters.http.grpc_web
+            typed_config:
+              "@type": type.googleapis.com/envoy.extensions.filters.http.grpc_web.v3.GrpcWeb
           - name: envoy.filters.http.cors
+            typed_config:
+              "@type": type.googleapis.com/envoy.extensions.filters.http.cors.v3.Cors
           - name: envoy.filters.http.router
+            typed_config:
+              "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router
   clusters:
   - name: echo_service
     connect_timeout: 0.25s