Introduce an attached volume migration test
This change introduces a true cinder host to host attached volume
migration test in addition to the existing attached volume retype test.
To enable this two new calls are introduced to the v3 volume client to
allow all volume backends to be listed per project and to also call for
a direct volume migration between backends.
Related-bug: #1803961
Depends-On: I1bdf3431bda2da98380e0dcaa9f952e6768ca3af
Change-Id: I501eb0cd5eb101b4dc553c2cdbc414693dd5b681
5 files changed