db: Migrate "qos specs" APIs to enginefacade
db: Migrate "qos specs" APIs to enginefacade

Migrate qos specs-related APIs from the legacy enginefacade to the
modern context-based enginefacade.

Change-Id: I34ff4c5e08569d21ccf4243a1ba27ec9f48a1ee9
Signed-off-by: Stephen Finucane <4725dc7f3632bf126d9fbdc30c347e91e8d2fe16@redhat.com>

mahak/cinder,openstack/cinder,mahak/cinder,openstack/cinder