Add support for biasing aggregation signatures. #1844

Job	Run time
Build	47m 56s
Spark Aggregate Fuzzer	16m 1s
Spark Fuzzer	15m 52s
Presto Fuzzer	15m 42s
Spark Bias Fuzzer	0s
Aggregate Fuzzer	15m 49s
Join Fuzzer	15m 39s
Exchange Fuzzer	15m 49s
Biased Aggregation Fuzzer with Presto as source of truth	17m 38s
Presto Bias Fuzzer	0s
Aggregation Fuzzer with Presto as source of truth	0s
Signature Changes	2s
	2h 40m 28s

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