Support volume cloning

[michaelbeaumont]

Is your feature request related to a problem? Please describe.
The CSI driver doesn't support volume cloning
so it's not possible to create a PVC from another PVC:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: storage-clone
spec:
  storageClassName: openebs-single-thin-replica
  dataSource:
    name: storage
    kind: PersistentVolumeClaim

throws warnings like:

failed to provision [...]: CSI driver does not support clone operations: controller CLONE_VOLUME capability is not reported

Cloning can be used, for example, with volsync to backup with clones

Describe the solution you'd like
Volume cloning supported by the replicated storage CSI driver.

Describe alternatives you've considered
Snapshots can be used instead as sources but cloning makes it a little easier to duplicate a volume and doesn't require creating a snapshot just to duplicate a volume.