Bar chart doesn't handle null data well

[CaliLuke]

Is your feature request related to a problem? Please describe.

Currently when displaying data with categorical labels, the bar chart doesn't have a way to either add a "null" category or remove it from display.

Describe the solution you'd like

Add a "null" category by default, and allow users to hide it or show it.

Describe alternatives you've considered

we could filter the values but the visualizations should be robust to a very common data issue.

How important is this feature to you?

very, it breaks most visualizations containing null data

Additional context

[flamber]

When using binning/granularity "Minute of hour" or "Hour of day", then null is added incorrectly to the first column of Line/Bar/Area chart.
There's a warning triangle "column" is an unaggregated field: if it has more than one value at a point on the x-axis, the values will be summed., but that's incorrect in this case.
And displaying with data points causes it to show double points for the first column.

Displaying as Row chart will correctly add null to a special "(empty)" bar - and it doesn't show a triangle, but that might be because of #12655:

Related to #11907

[alxnddr]

The same happens when the X axis is a numeric column that contains both 0 and null:

This is happening because of a bug in the crossfilter dependency
crossfilter/crossfilter#164

[alxnddr]

Fixed by #15554

Repro is needed, I will add in a separate PR