Class PushCountQueryAndTagsToSource


public class PushCountQueryAndTagsToSource extends PhysicalOptimizerRules.OptimizerRule<AggregateExec>
Pushes count aggregations on top of query and tags to source. Will transform:
  Aggregate (count(*) by x)
  └── Eval (x = round_to)
      └── Query [query + tags]
  
into:
  Filter (count > 0)
  └── StatsQuery [count with query + tags]
  
Where the filter is needed since the original Aggregate would not produce buckets with count = 0.