network: address interface should pair port:proto

As per the discussion here: https://github.com/envoyproxy/envoy/pull/17414

In a perfect world our Address interface should include proto with port, as the operating system treats TCP:1234 differently from UDP:1234. Unfortunately, this will have very large implications on the overall code structure. There are a few things we might consider here:

1. Remove port from the primary Address interface, as certain use cases do not actually care about port and proto. For example DNS, IP tagging, etc.
2. Introduce a AddressAndPort interface which includes an address as well as a port/proto pair. Then, any port must have an associated proto with it as well.

Either way this needs some thinking and prototyping.