Add helper methods to create cluster and storedefs
Add non-contiguous shuffle and cluster expansion planner test
Add non-contiguous zones/nodes tests to ZonedRebalanceBatchPlan

Added shuffle and cluster expansion tests to rebalancebatchplan
in presence of cluster with non contiguous zone and node ids.
StoreRouting plan tests with non contiguous zones/nodes
PartitionBalanceTest with non contiguous zone/node ids
ZoneRoutingStrategyTest with non-contiguous zone/node ids
RepartitionerTest with non contiguous zone/node ids
Address code review comments