Support creating aggregate objects using arbitrary SQL #2001

Job	Run time
Build	2m 46s
Test with ECJ	1m 39s
Integration Test (h2)	1m 52s
Integration Test (mysql)	2m 52s
Integration Test (mysql8)	2m 50s
Integration Test (postgresql)	2m 30s
Integration Test (sqlite)	1m 57s
Integration Test (sqlserver)	2m 49s
Integration Test (oracle)	2m 35s
Publish	0s
	21m 50s

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