[BarPlot] - Unifying HorizontalBar and VerticalBar

HorizontalBar plots and VerticalBar plots will be deprecated.  To replace them, a third argument isVertical has been added to AbstractBarPlot which is defaulted to true.

Also, AbstractBarPlot has been upgraded to not be abstract, thus it is renamed to Bar plot.

QE: Regression pass over ClusteredBar plot and StackedBar plot would be recommended as they are affected by Bar plot changes