DRILL-1707: Don't push Filter past Project if the Filter is referencing ITEM expression produced by the Project (this is done as part of a new rule). Enable a few tests in TestProjectPushDown and TestExampleQueries that were marked Ignored earlier.
DRILL-1673: Set the correct group count in splitAndTransferTo for repeated vectors Handle the case in FlattedRecordBatch where we return null internal vectors for repeated lists in the first schema batch
DRILL-1660: adding a test case to cover an array of empty and null valued objects. i) remove redundant guard statement from JsonRecordReader2 ii) rename unit test suite