Filtered aggregations nest incorrectly

[efronbs]

Currently FilteredAggregation nests incorrectly. It simply makes the filtered aggregation the inner query, and makes the outer query the aggregation it wraps without the filter. Some downstream customers have found this behavior generates erroneous nested queries. Specifically, if the wrapped aggregation relies on a fact dimension that is not grouped on, that dimension will not be exposed by the inner query making the outer query attempt to reference a dimension that doesn't exist in its context.

The fix is the call nest on the wrapped aggregation, and apply the filter to the inner query of the wrapped aggregation. the outer query of the wrapped aggregation simply becomes the outer query on the nesting that is returned (after naming has been correctly set of course)