[SliderIOS] Apply value after minimum/maximumValue in order to ensure it is properly set

[brentvatne]

value is clamped between min/max and so order of prop application matters - value always ended up being set first in my tests, and consequently a value outside of the default range 0-1 would not work. So this applies the value when the min/max are set.

Gist of broken example

^ the second slider here should have it's cursor in the middle

/cc @tadeuzagallo

[brentvatne]

While this solution works, I do wonder if it's worth adding a hook on view manager classes that allows us to specify in what order props should be applied, either in JS or Objective-C. eg: instead of having RCTSetViewProps [iterate over each prop in an unreliable order as provided by NSDictionary] the manager class could optionally expose a function that specifies order which RCTSetViewProps can then use to sort.

// RCTSliderManager.m

- (NSArray *)applyPropsFirst
{
  return @[ @"minimumValue", @"maximumValue" ];
}

or...

// RCTSliderManager.m

- (NSArray *)propsOrder
{
  return @[ @"minimumValue", @"maximumValue", @"value" ];
}

This would have been helpful for me on react-native-overlay because I need to ensure visible is set before setting the windowLevel here and on react-native-video because most things are dependent on the src being set.

@tadeuzagallo - thoughts? cc @vjeux

[brentvatne]

ping @tadeuzagallo - simple change here that we discussed in IRC, would be good to get it into next sync if possible

[nicklockwood]

I've been trying to land this today, but ran into an unexpected merge conflict. Should be sorted shortly.