Expose current index / detent

[maxRN]

We have the following use case: We have dismissable={false} but users can resize the sheet via the header. We also want them to be able to resize the sheet by pressing the back button on Android.
So if index === 1 then it should resize to 0 and if index === 0 then pressing back should navigate away from the page. The sheet is a permanent sheet that is always showing on this page.

However since the current index is not exposed anywhere (as far as I can tell) we have to manually track it using onDetentChange. It would be nicer if I can just say sheet.current?.getIndex() for example.

[lodev09]

That's exactly what onDetentChange event is for. This just adds extra complexity without any real benefit. I would prefer limiting ref methods as "commands".