Add testID to movingBox example

Summary:
Changelog:
[Internal] - Add testID to moving box example for testing

Reviewed By: yungsters

Differential Revision: D30824961

fbshipit-source-id: 1e25f25a49d064eee6e17aebc2d981648a0559bc

packages/rn-tester/js/examples/Animated/MovingBoxExample.js

@@ -78,7 +78,7 @@ function MovingBoxView({useNativeDriver}: {useNativeDriver: boolean}) {
   };
   return (
     <View style={styles.container}>
-      <View style={styles.boxContainer}>
+      <View testID="moving-view-track" style={styles.boxContainer}>
         {boxVisible ? (
           <Animated.View
             testID="moving-view"