Updating the SC cinder backend to support both iSCSI
and FC drivers. It is also enhanceded to support
multiple backends.
CinderScBackendName supports a list of backend names
and a new CindeScMultiConfig parameter provides
a way to specify parameter values for each backend.
For example see file environments/cinder-dellemc-sc-config.yaml
Depends-On: https://review.opendev.org/#/c/722538/
Change-Id: I6e5f3753fe167c7fbc75c3d382c88c09c247c7b3