Chart node improvement for stacked bars

### Description

Using chart node with stacked bars, there is no sum value of all bars added up. There is also no possibility to visualize the sum, as sending the sum value to the chart node would add another stack ontop, rather then showing as a sum bar.

Example: Bar 1: 10, Bar 2: 15, Bar 3: 20
The sum is 10+15+20=45


Possible improvement options:
A: Add the sum value in the mouse over/hover popup
B: Add a small bar next to the existing stacked bars to indicate the total sum and add the sum to the mouse over/hover popup
Example look (with green showing the sum of all values)


C: ??

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate