Stacked bar charts: doesn't stack multiple datas with same x coordinate for one dataset

### Expected behavior

I was expecting all datas to be stacked.

### Current behavior

In my example, I have always 2 values in same x coordinate ( one positive, one negative ). As you can see, the bars above 0 are not stacked whereas the ones below 0 are.

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### Reproducible sample

https://jsfiddle.net/6b7gweps/

### Optional extra steps/info to reproduce

_No response_

### Possible solution

- Changes on the function that performs the stack to stack every datas.

- Maybe add a stackBy property to tell the chart which property of the data you want to use to perform the stack
Example of one data object:
```
{
x: string,
y: number,
positive: boolean
}
```
And on the chart configuration:
`stackBy:['x','positive']`

### Context

I am using the stacked bar charts to represent the traffic In and traffic Out in bytes for multiple interfaces

### chart.js version

v4.2.1

### Browser name and version

_No response_

### Link to your project

_No response_