This ticket is to introduce the class that will become the new unsharded collection balancer policy. This policy will need to be created by the balancer, similar to the other policies. It will need to be able to return moveCollection information both for draining and for steady state balancing. The return value should contain all the information needed for the balancer commands scheduler to issue a moveCollection command. We may also need to introduce a struct similar to migrateInfo to encapsulate the return information.

This ticket should not include any of the logic for selecting migrations or fetching data size, it is just for the outline of the class that will contain this logic.