Add pointerEvents prop to RN Android scroll views

Summary:
Per discussion in the previous diff D33672110, it's ok to add the `pointerEvents` prop to scrollview. This will help prevent scrolling on the ScrollView if pointerEvents is set to `box-none`, or `none`.

Corresponding doc changes are in https://github.com/facebook/react-native-website/pull/2936

Changelog:
[Android][Added] - Add new API in ScrollView and HorizontalScrollView to process pointerEvents prop.

Reviewed By: javache

Differential Revision: D33699223

fbshipit-source-id: 1cae5113e9e7d988fc4c4765c41d817a321804c4

ReactAndroid/src/main/java/com/facebook/react/uimanager/PointerEvents.java

@@ -7,6 +7,8 @@
 
 package com.facebook.react.uimanager;
 
+import java.util.Locale;
+
 /**
  * Possible values for pointer events that a view and its descendants should receive. See
  * https://developer.mozilla.org/en-US/docs/Web/CSS/pointer-events for more info.
@@ -25,4 +27,16 @@ public enum PointerEvents {
   /** Container and all of its children receive touch events (like pointerEvents is unspecified). */
   AUTO,
   ;
+
+  public static PointerEvents parsePointerEvents(String pointerEventsStr) {
+    return PointerEvents.valueOf(pointerEventsStr.toUpperCase(Locale.US).replace("-", "_"));
+  }
+
+  public static boolean canBeTouchTarget(PointerEvents pointerEvents) {
+    return pointerEvents == AUTO || pointerEvents == PointerEvents.BOX_ONLY;
+  }
+
+  public static boolean canChildrenBeTouchTarget(PointerEvents pointerEvents) {
+    return pointerEvents == PointerEvents.AUTO || pointerEvents == PointerEvents.BOX_NONE;
+  }
 }