Type from the tooltip y title formatter is missing arguments

[cyrilf]

I'm using Typescript and a chart of type heatmap.

On the configuration object, based on the documentation & types I have:

const options: ApexOptions = {
  chart : { ... },
  tooltip: {
    y: {
      title: {
        formatter: (seriesName: string): string => {
          // Do stuff
        },
     }
   }
};

But actually, formatter accept 2 more arguments.
So it could be nice to reflect it on the types and/or docs.

Something like this:

formatter: (seriesName: string, opts: { series: number[][]; seriesIndex: number; dataPointIndex: number }, w: any): string

I haven't open a PR because I don't find the perfect type for series and for w.
Here is the line to update on the types file.

You can see that the second and third arguments are passed on this file everytime that the function yLbTitleFormatter is called.

https://github.com/apexcharts/apexcharts.js/blob/abf93e3e40d35785245c224913b4e4e61457e1ac/src/modules/tooltip/Labels.js

If you know the correct type for series and w, I can open a PR.