Fixed #16087 -- Added ResolverMatch instance to test client response

hmm, not sure how to go about this here, as we would need to pass along the request object, or even just the PATH_INFO. Any tips?

Not sure how expensive it is, it seems to loop over all the url patterns and tries to resolve each of them. This is why I initially added this to the base handler, to save doing this again.

Alternatively, what would you think of storing the resolver_match from BaseHandler as something like `self._resolver_match`. That way, the ClientHandler class would be able to access it. Just a thought...