[New Feature] need wheel's disabled option #712

What problem does this feature solve?

I use the wheel to make a picker like demo.Now I want to create some options which can't be picked.

What does the proposed API look like?

like:

wheel:{
  selectedIndex: 0,
  rotate: 25,
  adjustTime: 400,
  wheelWrapperClass: 'wheel-scroll',
  wheelDisabledItemClass: 'wheel-disabled-item',
  wheelItemClass: 'wheel-item'
}

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