Add GetSnapshotClass to VolumeHelper interface

Add a GetSnapshotClass method to VolumeHelper that encapsulates the
extraction of the snapshotClass parameter from volume policy actions.
This avoids requiring callers to parse raw parameters from
GetActionParameters. Simplify the CSI plugin to use the new method.

Ref: #8807

Signed-off-by: Shubham Pampattiwar <spampatt@redhat.com>

internal/volumehelper/volume_policy_helper.go

@@ -430,6 +430,21 @@ func (v *volumeHelperImpl) GetActionParameters(obj runtime.Unstructured, groupRe
 	return false, "", nil, nil
 }
 
+func (v *volumeHelperImpl) GetSnapshotClass(obj runtime.Unstructured, groupResource schema.GroupResource) (string, error) {
+	matched, actionType, params, err := v.GetActionParameters(obj, groupResource)
+	if err != nil {
+		return "", err
+	}
+	if !matched {
+		return "", nil
+	}
+	action := &resourcepolicies.Action{
+		Type:       resourcepolicies.VolumeActionType(actionType),
+		Parameters: params,
+	}
+	return action.GetSnapshotClass()
+}
+
 func (v *volumeHelperImpl) shouldIncludeVolumeInBackup(vol corev1api.Volume) bool {
 	includeVolumeInBackup := true
 	// cannot backup hostpath volumes as they are not mounted into /var/lib/kubelet/pods