void addNewResource(String resourceName, IdealState idealState) throws Exception {
    resourcesToIdealStates.put(resourceName, idealState);
    triggerIdealStateChangeNotification();
  }
Add new resource and its associated ideal state into cluster (Note that, each dc has its own HelixAdmin so resource
is actually added into dc where current HelixAdmin sits). This would trigger ideal state change which should be captured
by Helix Cluster Manager on each node.
@param resourceName name of resource. (The resource may contain one or more partitions)
@param idealState ideal state associated with the resource. (it defines location of each replica from each partition)
@throws Exception
ambry-clustermap/src/test/java/com/github/ambry/clustermap/MockHelixAdmin.java