Adding CLASS aggregator to Stats Infra - it generates a hash from a set of column values, to classify output rows according to the corresponding columns. Systemless test is included

Change-Id: I11ecc1181ae85b9d85fd774dad90f17ef62d8f3c
Merge "Adding CLASS aggregator to Stats Infra - it generates a hash from a set of column values, to classify output rows according to the corresponding columns. Systemless test is included"