* initial commits for finalizeFieldAccess #2433
* fix some bugs to run a query
* change name of method Queries.verifyAggregations to Queries.prepareAggregations
* add Uts
* fix Ut failures
* rebased to master
* address comments and add a Ut for arithmetic post aggregators
* rebased to the master
* address the comment of injection within arithmetic post aggregator
* address comments and introduce decorate() in the PostAggregator interface.
* Address comments. 1. Implements getComparator in FinalizingFieldAccessPostAggregator and add Uts for it 2. Some minor changes like renaming a method name.
* Fix a code style mismatch.
* Rebased to the master
* Add PostAggregators to generator cache keys for top-n queries
* Add tests for strings
* Remove debug comments
* Add type keys and list sizes to cache key
* Make post aggregators used for sort are considered for cache key generation
* Use assertArrayEquals()
* Improve findPostAggregatorsForSort()
* Address comments
* fix test failure
* address comments