Handle failure cases on startup gracefully to avoid causing cascading
errors and poor initialization in other components. Initial errors from
config load cause the initializer to pause and hold requests. Return
typed errors to better communicate failures to clients.
Add code to handle two specific cases - admin wants to bypass
initialization defaulting, and mirror pods (which want to bypass
initialization because the kubelet owns their lifecycle).
Automatic merge from submit-queue (batch tested with PRs 44440, 44038, 44302, 44316, 43876)
Extend the gc admission plugin to check ownerReference.blockOwnerDeletion
#Extend the gc admission plugin to prevent user who doesn't have delete permission of the *owner* from changing blockOwnerDeletion field of existing ownerReferences, or adding ownerReference with blockOwnerDeletion=true.
The plugin need a RESTMapper to translate ownerRef.Kind to Resource. It should be using a dynamic one. However, as discussed in https://github.com/kubernetes/kubernetes/pull/42615, such a RESTMapper will be built after watchable discovery API is implemented, so in this PR the plugin is using the `api.Registry.RESTMapper()`, which is also [used](https://github.com/kubernetes/kubernetes/blob/master/cmd/kube-controller-manager/app/core.go#L165-L166) by the garbage collector currently.
```release-note
Extending the gc admission plugin so that a user who doesn't have delete permission of the *owner* cannot modify blockOwnerDeletion field of existing ownerReferences, or add new ownerReference with blockOwnerDeletion=true
```
cc @lavalamp
