Enhance hbase coprocessor aggregation operations:GLOBAL_MIN, LATEST_MIN etc and FINAL attributes

As part of YARN-4062, Joep and I had been discussing about min, max operations and the final attributes.

YARN-4062 has GLOBAL_MIN, GLOBAL_MAX and SUM operations. It presently indicates SUM_FINAL for a cell that contains a metric that is the final value for the metric.

We should enhance this such that the set of aggregation dimensions SUM, MIN, MAX, etc. are really set of a per-column level and shouldn't be passed from the client, but be instrumented by the ColumnHelper infrastructure instead. We should probably use a different tag value for that.

Both aggregation dimension and this "FINAL_VALUE" or whatever abbreviation we use are needed to determine the right thing to do for compaction. Only one value needs to have this final value bit / tag set.