check 'desired_capacity' when recovering cluster

The BP is about checking desired_capacity(the real number of nodes the cluster should have) when recovering cluster.
Which means, we will create nodes when the number of nodes in the cluster is less than 'desired_capacity', otherwise, we will
delete nodes from the cluster.

The plan:

1. Add parameter to ClusterRecoverRequest API called "check_capacity"
2. Do check and trigger action in engine service layer.
    Trigger CLUSTER_RESIEZE if needed, make sure this action will be executed before CLUSTER_RECOVER