Refactor AggregationResponse (#368)

Author: vanjaftn

modules/integration/src/test/scala/zio/elasticsearch/HttpExecutorSpec.scala

@@ -467,7 +467,7 @@ object HttpExecutorSpec extends IntegrationSpec {
             Executor.execute(ElasticRequest.createIndex(firstSearchIndex)),
             Executor.execute(ElasticRequest.deleteIndex(firstSearchIndex)).orDie
           ),
-          test("aggregate using terms aggregation") {
+          test("aggregate using terms aggregation with max aggregation as a sub aggregation") {
             checkOnce(genDocumentId, genTestDocument, genDocumentId, genTestDocument) {
               (firstDocumentId, firstDocument, secondDocumentId, secondDocument) =>
                 for {
@@ -481,7 +481,9 @@ object HttpExecutorSpec extends IntegrationSpec {
                            .refreshTrue
                        )
                   aggregation =
-                    termsAggregation(name = "aggregationString", field = TestDocument.stringField.keyword)
+                    termsAggregation(name = "aggregationString", field = TestDocument.stringField.keyword).withSubAgg(
+                      maxAggregation("subAggregation", TestDocument.intField)
+                    )
                   aggsRes <-
                     Executor
                       .execute(ElasticRequest.aggregate(selectors = firstSearchIndex, aggregation = aggregation))