Treat staging repos as authoritative for all files
Treat staging repos as authoritative for all files

Move files from kubernetes/foo root back to
kubernetes/kubernetes/staging/src/k8s.io/foo root

Then:
- add CONTRIBUTING.md for all staging repos
- add .PULL_REQUEST_TEMPLATE to all staging repos
- ignore .github while diffing generated protobuf

Kubernetes-commit: d9b5773101e930431f24fe178d988271c1becc35

kubernetes/apiserver,kubernetes/apiserver