Histogram should be less opinionated and accept a data column for the count axis (y-axis)

Currently, Histogram calculates the count axis, generally the y-axis, on its own based on the given data table.

There should be flexibility to allow a data column to be specified in the config for the count axis.

Start by locating the Histogram implementation and its configuration types. Trace how the count axis is currently derived from the data table, then determine how a configured data column should override that behavior. Done means Histogram accepts the configured count-axis column while preserving existing behavior when none is specified.

Written by the indexing model from the issue text.