Add compatibility test for accumulator operators (13 total)

[eerxuan]

core operator accumulators - - bottom
core operator accumulators - - bottomN
core operator accumulators - - count
core operator accumulators - - firstN
core operator accumulators - - lastN
core operator accumulators - - maxN
core operator accumulators - - median
core operator accumulators - - minN
core operator accumulators - - percentile
core operator accumulators - - stdDevPop
core operator accumulators - - stdDevSamp
core operator accumulators - - top
core operator accumulators - - topN