Automatic merge from submit-queue
Add encryption to EBS dynamic provisioner
Resolves https://github.com/kubernetes/kubernetes/issues/30792
Adds encryption to the EBS cloud provider and provisioner.
Follow up to #29006 (all commits but the one in this PR will drop out).
@kubernetes/sig-storage
```release-note
```
The README for persistent volume provisioning had information about the
hostpath provisioner for testing purposes, but lacked instructions on
how to enable it.
HostPath volumes are not automatically provisioned unless we pass in `--enable-hostpath-provisioner` to the controller manager. This was not mentioned in the docs previously.
