<bmx-pivot-slicer>
A slicer for a bmx-pivot-grid.
Click members to filter. Each slicer shows how many records its members have under the other
slicers' choices; the channel slicer hides the ones that would leave nothing. The channel is not placed on the
pivot at all - a slicer can filter any field.
Every property, event and method: https://docs.binarymission.co.uk/webcomponents/bmx/bmx-pivot-slicer.html