[dev][cinder] snapshot revert to any point

Hi, There is a lack of feature to revert to any snapshot point in supported drivers like RBD. I've made a change to support this feature. Can someone please review them? https://review.opendev.org/c/openstack/cinder-tempest-plugin/+/812032 https://review.opendev.org/c/openstack/cinder/+/806807 Thanks