Add isPressable native prop to Text

Summary:
react-native-windows currently needs to maintain a fork of TextNativeComponent to wire through a native-only prop for `isPressable`.

The reason we do this on Windows is that we implement an optimization so we only attempt to hit test a virtual Text node if it is actually pressable, leading to significant perf improvement for pointer events (e.g., onMouseEnter / onMouseLeave) on Text.

Changelog:
[General][Added] - Native-only prop to optimize text hit testing on some RN platforms

Reviewed By: JoshuaGross

Differential Revision: D32564637

fbshipit-source-id: bf47c68d94a930d2c620cb3b1584355c5e412bd4

Author: rozele

Libraries/Text/Text.js

@@ -163,6 +163,7 @@ const Text: React.AbstractComponent<
       {...restProps}
       {...eventHandlersForText}
       isHighlighted={isHighlighted}
+      isPressable={isPressable}
       numberOfLines={numberOfLines}
       selectionColor={selectionColor}
       style={style}

Libraries/Text/TextNativeComponent.js

@@ -19,13 +19,18 @@ type NativeTextProps = $ReadOnly<{
   ...TextProps,
   isHighlighted?: ?boolean,
   selectionColor?: ?ProcessedColorValue,
+  // This is only needed for platforms that optimize text hit testing, e.g.,
+  // react-native-windows. It can be used to only hit test virtual text spans
+  // that have pressable events attached to them.
+  isPressable?: ?boolean,
 }>;
 
 export const NativeText: HostComponent<NativeTextProps> =
   (createReactNativeComponentClass('RCTText', () => ({
     validAttributes: {
       ...ReactNativeViewAttributes.UIView,
       isHighlighted: true,
+      isPressable: true,
       numberOfLines: true,
       ellipsizeMode: true,
       allowFontScaling: true,
@@ -59,6 +64,7 @@ export const NativeVirtualText: HostComponent<NativeTextProps> =
         validAttributes: {
           ...ReactNativeViewAttributes.UIView,
           isHighlighted: true,
+          isPressable: true,
           maxFontSizeMultiplier: true,
         },
         uiViewClassName: 'RCTVirtualText',