Rebalance as a Resource

Represent rebalances as resources that allow customers to interact with. Including pause/cancel

Operator would, before triggering a rebalance create a k8s resource called CouchbaseRebalance resource that targets the cluster specified. Customers could also create a CouchbaseRebalance resource to trigger a rebalance of a cluster.

There should be an operator configuration for "Rebalance Delay" that specifies how long Operator should wait from the creation of a rebalance resource before beginning the rebalance with a default of 0seconds (as soon as operator sees the rebalance resource, it can begin the rebalance)

Once the rebalance has been kicked off, operator should update the rebalance object with information regarding the rebalance. eg status events for % completion, the task Id of the rebalance, the rebalance report file path, etc.

Once operator has detected that the rebalance has successfully completed, operator will preserve the last N rebalances (configurable at operator deployment), and delete any CouchbaseRebalance resources older.