Support Animated.event extracting values from array

Summary:
`onPointerMove` events get dispatched with an `offset: [x, y]` attribute (API is not yet available in OSS, so subject to change), but `EventAnimationDriver` in RN Android is not able to extract values with such keys (even though the equivalent JS implementation does allow it).

(TODO: verify iOS behaviour)

Changelog:
[General][Added] - Animated.event can be used to extract values with numeric keys from native events

Reviewed By: mdvacca

Differential Revision: D32531117

fbshipit-source-id: 918a5443c5d8f5f8200d86bb67f84e8bc175c1d3

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

@@ -8,7 +8,10 @@
 package com.facebook.react.animated;
 
 import androidx.annotation.Nullable;
+import com.facebook.react.bridge.ReadableArray;
 import com.facebook.react.bridge.ReadableMap;
+import com.facebook.react.bridge.ReadableType;
+import com.facebook.react.bridge.UnexpectedNativeTypeException;
 import com.facebook.react.bridge.WritableArray;
 import com.facebook.react.bridge.WritableMap;
 import com.facebook.react.uimanager.events.RCTEventEmitter;
@@ -31,12 +34,45 @@ public void receiveEvent(int targetTag, String eventName, @Nullable WritableMap
     }
 
     // Get the new value for the node by looking into the event map using the provided event path.
-    ReadableMap curMap = event;
+    ReadableMap currMap = event;
+    ReadableArray currArray = null;
     for (int i = 0; i < mEventPath.size() - 1; i++) {
-      curMap = curMap.getMap(mEventPath.get(i));
+      if (currMap != null) {
+        String key = mEventPath.get(i);
+        ReadableType keyType = currMap.getType(key);
+        if (keyType == ReadableType.Map) {
+          currMap = currMap.getMap(key);
+          currArray = null;
+        } else if (keyType == ReadableType.Array) {
+          currArray = currMap.getArray(key);
+          currMap = null;
+        } else {
+          throw new UnexpectedNativeTypeException(
+              "Unexpected type " + keyType + " for key '" + key + "'");
+        }
+      } else {
+        int index = Integer.parseInt(mEventPath.get(i));
+        ReadableType keyType = currArray.getType(index);
+        if (keyType == ReadableType.Map) {
+          currMap = currArray.getMap(index);
+          currArray = null;
+        } else if (keyType == ReadableType.Array) {
+          currArray = currArray.getArray(index);
+          currMap = null;
+        } else {
+          throw new UnexpectedNativeTypeException(
+              "Unexpected type " + keyType + " for index '" + index + "'");
+        }
+      }
     }
 
-    mValueNode.mValue = curMap.getDouble(mEventPath.get(mEventPath.size() - 1));
+    String lastKey = mEventPath.get(mEventPath.size() - 1);
+    if (currMap != null) {
+      mValueNode.mValue = currMap.getDouble(lastKey);
+    } else {
+      int lastIndex = Integer.parseInt(lastKey);
+      mValueNode.mValue = currArray.getDouble(lastIndex);
+    }
   }
 
   @Override