Allow async callback function in bubbleSlides Array

[lunaticcoding]

Is your feature request related to a problem? Please describe.
Some of the widgets I need to be scrolled to first, before highlighting them.

Describe the solution you'd like
Inside the bubbleSlides array, allow for void and async returns. Something like

bubbleSlides: [
      BubbleSlide(key1),
      () async {
            await Scrollable.ensureVisible(key2.currentContext);
      }(),
      BubbleSlide2(key2),
],

Describe alternatives you've considered
Other Packages allow for this feature but don't provide enough flexibility with regards to where to place the explanation text for the highlighted widget.

Additional context
Add any other context or screenshots about the feature request here.

[Skyost]

Other Packages allow for this feature but don't provide enough flexibility with regards to where to place the explanation text for the highlighted widget.

Can you please provide me an example of such packages ?

[lunaticcoding]

showcaseview allows it. I can simply do the following:

WidgetsBinding.instance.addPostFrameCallback((_) async {
        ShowCaseWidget.startShowCase(context, [_one, ]));
        await Scrollable.ensureVisible(_two.currentContext);
        ShowCaseWidget.startShowCase(context, [_two, _three]);
});