Unify generic proxy code in apimachinery
Unify generic proxy code in apimachinery

Make the utility package truly generic, consolidate all generic proxy in
apimachinery.

Kubernetes-commit: edc12aafe2fbfe3475bdf03c34ffa26cc4322673

kubernetes/kube-aggregator,kubernetes/kube-aggregator,caesarxuchao/kube-aggregator,caesarxuchao/kube-aggregator,caesarxuchao/kube-aggregator