[Enhancement] iOS PlatformSpecific for UISlider

[rmarinho]

Rationale

There is currently no way to to set the value when tapping a slider on iOS

Implementation.

Add a PlatformSpecific property for Slider on iOS. Customer renderer changes to subscribe to the tap event, calculate position and set the value. `((IElementController)Element).SetValueFromRenderer(Slider.ValueProperty, Value)

Slider.On<iOS>().UpdateOnTap(true/false);

Expected Result

Android

None

iOS

Value of slider should be updated when tapping

UWP

None

Implications for CSS

None

Backward Compatibility

We should set default to false and make sure all custom renderers continue to work even with our implementation.
Should respect and have some UITest for InputTransparent and and IsEnabled properties.
Should work with a tap gesture by allowing bubbling of the event to the parent.

Difficulty: Easy

[ctartamella]

I would like to take this one. @davidortinau

[jassmith]

@ctartamella still working on this?

[henricm]

@davidortinau I'll take a look on this now as it seems like there is no active work going on. Let me know if there is.