volume snapshot tree

Currently there is no way to determine volume-snapshot-volume tree.

steps: Create new option for cinder CLI (--parents) or another to show volume-snapshot-volume tree.

# cinder --parents <VOLUME_OR_SNAPSHOT_ID> (SNAPSHOT_ID2 or another VOLUME_ID1)

<VOLUME_ID1>
    |
    -----<SNAPSHOT_ID1>
                        |
                        -----<VOLUME_ID2>
                                       |
                                        -----<SNAPSHOT_ID2>
                                                                    |
                                                                     -----<VOLUME_ID3>