[Fabric] Convert UISlider to RCTSlider shim (microsoft#1525)

* [Fabric] Replace UIKit with RCTUIKit

* [Fabric] Convert UISlider to RCTUISlider shim

* Add macOS tags

* Refactor RCTSlider to RCTUISlider for Fabric

Co-authored-by: Shawn Dempsey <shawndempsey@fb.com>

Author: shwanton

React/Base/RCTUIKit.h

@@ -468,3 +468,14 @@ NS_INLINE CGRect CGRectValue(NSValue *value)
 }
 
 #endif // ] TARGET_OS_OSX
+
+//
+// fabric component types
+//
+
+#if !TARGET_OS_OSX // [TODO(macOS GH#774)
+#define RCTUISlider UISlider
+#else
+@interface RCTUISlider : NSSlider
+@end
+#endif // ]TODO(macOS GH#774)

React/Fabric/Mounting/ComponentViews/Slider/RCTSliderComponentView.mm

@@ -23,7 +23,7 @@ @interface RCTSliderComponentView () <RCTImageResponseDelegate>
 @end
 
 @implementation RCTSliderComponentView {
-  UISlider *_sliderView;
+  RCTUISlider *_sliderView; // TODO(macOS GH#774)
   float _previousValue;
 
   UIImage *_trackImage;
@@ -48,7 +48,7 @@ - (instancetype)initWithFrame:(CGRect)frame
     static const auto defaultProps = std::make_shared<const SliderProps>();
     _props = defaultProps;
 
-    _sliderView = [[UISlider alloc] initWithFrame:self.bounds];
+    _sliderView = [[RCTUISlider alloc] initWithFrame:self.bounds]; // TODO(macOS GH#774)
 
     [_sliderView addTarget:self action:@selector(onChange:) forControlEvents:UIControlEventValueChanged];
     [_sliderView addTarget:self
@@ -284,17 +284,17 @@ - (void)setThumbImage:(UIImage *)thumbImage
   [_sliderView setThumbImage:thumbImage forState:UIControlStateNormal];
 }
 
-- (void)onChange:(UISlider *)sender
+- (void)onChange:(RCTUISlider *)sender // TODO(macOS GH#774)
 {
   [self onChange:sender withContinuous:YES];
 }
 
-- (void)sliderTouchEnd:(UISlider *)sender
+- (void)sliderTouchEnd:(RCTUISlider *)sender // TODO(macOS GH#774)
 {
   [self onChange:sender withContinuous:NO];
 }
 
-- (void)onChange:(UISlider *)sender withContinuous:(BOOL)continuous
+- (void)onChange:(RCTUISlider *)sender withContinuous:(BOOL)continuous // TODO(macOS GH#774)
 {
   float value = sender.value;