Create simulators for storage backends for end to end testing in the absence of real storage hardware

[joseph-v]

Issue/Feature Description: Currently end to end test for delfin including storage drivers requires storage hardware. By simulating storage array responses in software we can verify delfin features end to end.

Why this issue to fixed / feature is needed(give scenarios or use cases):

How to reproduce, in case of a bug:

Other Notes / Environment Information: (Please give the env information, log link or any useful information for this issue)