Related changes:
- hard-fail the xDS connection attempt if the envoy version is known to be too old to be supported
- remove the RouterMatchSafeRegex proxy feature since all supported envoy versions have it
- stop using --max-obj-name-len (due to: envoyproxy/envoy#11740)
* 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()
