Android: Try using cursor rect instead of item rect for soft keyboard panning

With a very large input item, you might get in the situation where a cursor at the very top of the item is panned out of the screen when you open the virtual keyboard, since Android only pans the window contents based on the input item rect so that the keyboard attaches to the bottom of the item.

An alternative to this would be to use the cursor rect instead for making the QtEditText focus item on Android. This is similar to what we plan to do on iOS. We would then need to make sure that we can update the position of the rectangle as you are typing, so that the window contents keep panning to always keep the cursor visible.