Pretty-print Native AnimatedNode values

Summary:
For debugging, add prettyPrint method to AnimatedNode classes.

Changelog: [Internal]

Reviewed By: shergin

Differential Revision: D22752292

fbshipit-source-id: ce1f08fc4fd97f38629dd82151c6ea762026c7c9

ReactAndroid/src/main/java/com/facebook/react/animated/ValueAnimatedNode.java

@@ -60,4 +60,8 @@ import com.facebook.react.bridge.ReadableMap;
   public void setValueListener(@Nullable AnimatedNodeValueListener listener) {
     mValueListener = listener;
   }
+
+  public String prettyPrint() {
+    return "ValueAnimatedNode[" + mTag + "]: value: " + mValue + " offset: " + mOffset;
+  }
 }