During the rollout of the 2.0 major version, these were removed because they were always out of sync. Add them back in.

This revealed an incompatibility once Werkzeug 2.1 is released, since it removedas_tuple but Flask's test client still passes it. Given that users have already been seeing a deprecation warning from Werkzeug, I'm adding the deprecation here as well, to be removed in Flask 2.1.

as_tuple would return(environ, response), now aTestResponse instance is always returned.response.request.environ has the same information.