Support more timeout settings

Description: In an effort of improving our Envoy Gateway security (especially DoS security), we are missing 3 timeout settings that are supported in Envoy Proxy but not exposed in Envoy Gateway CRDs.

The settings are:

• listener_filters_timeout
• request_headers_timeout
• transport_socket_connect_timeout

Do the maintainers see any issue with exposing these settings? If not then I would propose adding them to ClientTrafficPolicy API since they are all settings between Downstream and Envoy Proxy.

To be specific:

• listener_filters_timeout -> ClientTrafficPolicy.spec.timeout.filtersTimeout?
  • Not sure where this fits 🤔
• request_headers_timeout -> ClientTrafficPolicy.spec.timeout.http.requestHeadersTimeout
• transport_socket_connect_timeout --> ClientTrafficPolicy.spec.timeout.tcp.transportSocketConnectTimeout or ClientTrafficPolicy.spec.tls.connectTimeout

I am willing to submit a PR that introduces them once (if) this issue gets accepted.