Spec to implement feature in drivers to rotate credentials with
supporting API. Automates recreation and deletion of driver-defined
credentials when invoked via client or Horizon for the purpose of
cluster ownership change, user role change, or periodic rotation.
Change-Id: I084400a57f3c2a91ea1f695c1f8897e2b81f60e7
Signed-off-by: Matthew Northcott <matthewnorthcott@catalystcloud.nz>