feat: export cancelScroll handle

[bytemain]

I am creating an AI Chat-like app. The last item is growing in height when the AI generates some message.

At a very special moment (not always reproducible), when the last item is growing in height and I use the wheel to scroll up, the scrollbar will first scroll up and then immediately snap to the bottom.

After doing some research, this is caused by waitForMeasurement: when a user triggers a scrollToIndex, virtua will do scrolling and listen for the UPDATE_SIZE_EVENT event within the next 150ms. If at the same time, the last item is resizing, it will fire an action ACTION_ITEM_RESIZE to make the scroller scroll to the latest position. So if a user scrolls up within this 150ms, their operation will be overwritten by the latest scroll to the bottom.

here I add a new cancelScroll method to release the 150ms listener when user scroll up.

Creating a demo will consume amount of my time, So I didn't provide one, if you need a reproducible demo or have any question, please let me know

[bytemain]

May have another fix, when virtua detected user's scroll event, it will cancel the unfinished resize event listener