When consul is restarted and an envoy that had already sent
DiscoveryRequests to the previous consul process sends a request to the
new process it doesn't respect the setting and never populates
DiscoveryRequest.Node for the life of the new consul process due to this
bug: https://github.com/envoyproxy/envoy/issues/9682Fixes#8430
* Add support for ingress-gateway in CLI command
- Supports -register command
- Creates a static Envoy listener that exposes only the /ready API so
that we can register a TCP healthcheck against the ingress gateway
itself
- Updates ServiceAddressValue.String() to be more in line with Value()