Add GlutenAggregatorUtil to expose APIs into gluten (#476)

(cherry picked from commit 890b6d7)
(cherry picked from commit 0abe87e)
(cherry picked from commit 5a0a20e)
(cherry picked from commit 632a683)
(cherry picked from commit 234ed86)
(cherry picked from commit 40e7ab8)
(cherry picked from commit d387f5b)
(cherry picked from commit 9f6821b)
(cherry picked from commit 68c02df)
(cherry picked from commit 80c55c3)

src/Interpreters/Aggregator.h

@@ -1300,6 +1300,7 @@ class Aggregator final
     friend class ConvertingAggregatedToChunksSource;
     friend class ConvertingAggregatedToChunksWithMergingSource;
     friend class AggregatingInOrderTransform;
+    friend class GlutenAggregatorUtil;
 
     /// Data structure of source blocks.
     Block header;