Add VolumeGroupSnapshot API definition, including CRD, client,

informer and lister generated code.
Update ./client/hack/README with instructions to update the client
directory.

client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml

@@ -3,8 +3,8 @@ apiVersion: apiextensions.k8s.io/v1
 kind: CustomResourceDefinition
 metadata:
   annotations:
-    controller-gen.kubebuilder.io/version: v0.8.0
-    api-approved.kubernetes.io: "https://github.com/kubernetes-csi/external-snapshotter/pull/665"
+    controller-gen.kubebuilder.io/version: v0.11.3
+    api-approved.kubernetes.io: "https://github.com/kubernetes-csi/external-snapshotter/pull/814"
   creationTimestamp: null
   name: volumesnapshotcontents.snapshot.storage.k8s.io
 spec:
@@ -172,6 +172,7 @@ spec:
                     description: 'UID of the referent. More info: https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#uids'
                     type: string
                 type: object
+                x-kubernetes-map-type: atomic
             required:
             - deletionPolicy
             - driver
@@ -239,6 +240,10 @@ spec:
                   that dynamic snapshot creation has either failed or it is still
                   in progress.
                 type: string
+              volumeGroupSnapshotContentName:
+                description: VolumeGroupSnapshotContentName is the name of the VolumeGroupSnapshotContent
+                  of which this VolumeSnapshotContent is a part of.
+                type: string
             type: object
         required:
         - spec