Send a full instance via rpc for check_can_live_migrate_destination.
Send a full instance via rpc for check_can_live_migrate_destination.

Change the check_can_live_migrate_destination method of the compute
rpc API to take a full instance over rpc instead of just the instance
UUID.  This cuts down on database access needed by nova-compute.

Part of blueprint no-db-messaging.

Change-Id: I98a403fc4af7c3660c5144e532a318151c6c3b54

n0ano/gantt,n0ano/gantt