Visualizations: support negative values in bar chart

[stereobooster]

At the moment we don't handle case when there are negative values in metric variable

[micha-f]

This is a classic issue for bar charts but one that @ImogenF has solved before. There might also be an issue with bar charts on axes that do not include 0.

[ImogenF]

I plan on looking through the old visualization code at some point and finding all of the edge cases we accounted for, to make sure we have them in the new charts.