Tooltip: configure hideEmptySeries to only hide series with null values

[msigurd]

Summary

I have a line chart with both 0.00 and null values.
Right now hideEmptySeries also hides the series when the value is 0.00. I don't want that.

API Changes

So it would be nice to have an option like this:

tooltip: {
  hideEmptySeries: {
    hideZero: false,
  }
}

Or maybe a new configuration:

tooltip: {
  hideSeriesWithValues: [null, undefined, 0],
}

Intended Use Case

It would be useful for when you have charts where 0 is an important value, but null is not.
In my case this would be used in a price chart.