Allow kubectl port-forward to use "services"

[akram]

kubectl port-forward should give the ability to forward trafic to a service not only a pod.

This is convenient for developer/debugging purposes and especially for non HTTP/SNI protocols that cannot use routes and that we don't want to expose through nodePort.

Implementation could be done using the /proxy url to send trafic to the service, and netcat/socat to handle it through a local port.

It may require to add an additional flag --service=service-name or use the svc/<svc_name> syntax

[liggitt]

@kubernetes/sig-cli-feature-requests

[shahidhk]

Duplicate of #15180