fix t17697 Mobile SpinWheel does not operate correctly using VoiceOver.

- When VoiceOver is enabled on iOS, user is now able to operate the SpinWheelSlot with a double-tap-hold gesture to change the value.
- Add partial support Keyboard for navigation with VoiceOver: user can navigate and select a slot, but it is impossible to change the value (VoiceOver doesn't send keyboard events back to javascript).
- Add support for keyboard navigation with JAWS:
 - Add left/right arrow navigation support.
 - Add pageup/pagedown navigation support. Use the new property "pageSteps" to specify the number of element per page. default is 1.