[TIMOB-14776] Android: Add support for pagingControlHeight to ScrollableView

The size of the triangle controls on the Android scrollableview cannot be changed. They are way too large by default, made even worse if the scrollableview doesn't fill the screen. Expected Behavior: I should be able to change the height/width of the triangle controls with code like this:

"#myScrollableView[platform=android]": {
    height: 120, width: 100,
    pagingControlHeight: 8
}

Actual Behavior: That code has no effect. See the attached screen shot of a deliberately small scrollableview (the green box).