Add "snapshot_manage" Rbac test

This PS adds Rbac test for "snapshot_manage" policy [0],
api-ref[1]

[0]https://github.com/openstack/cinder/blob/0cf910d4345c000e8c306b1cb2b2dd291975cf71/cinder/policies/manageable_snapshots.py
[1]https://developer.openstack.org/api-ref/block-storage/v3/#manage-an-existing-snapshot

Change-Id: Iafbbd33e96f77a14591170d4f8eadc1a2c3c1ec8
1 file changed