I just noticed that the current router idle timeout only applies to the response half of the request-response pair. Along with the per-data-frame timeouts in #1778 it'd be good to have overall timeouts on the request path.

As discussed offline with Matt, we think the best option is to basically copy (and deprecate) the request timeout logic currently in the buffer filter, and implement in the HttpConnectionManager. This could still be applied on a per-route basis, but needs to be implemented in the HCM as there may be a significant delay between the http connection maanger receives them and when the router filter receives them.