[Enhancement] Adding standard deviation in the visualization boxplot

[VincentGardeux]

Request from Jonathan

In the visualization display, when one moves the mouse over the bars in the bar chart results, it displays "mean", "max", "median", etc. Would it be possible to also calculate "standard deviation" and have it in the mouse-over display?

For e.g. in the box plots in the evidences section, or in the visualization > Continuous > metadata