Idea: check for Pod containerPort for every ServicePort

[esnible]

Enhancement idea:

See istio/istio#15633

I spent four hours before understanding the problem of missing containerPort on a Service. istio-vet does not detect it.

[nrjpoddar]

Thanks @esnible for filing this enhancement. This makes sense to add as if you don't specify container ports the proxy interception will not happen.