Fix content:// uris not loading in Nodes

Summary:
In Ads Manager, images weren't loading when they were using
content:// as their uri.

Differential Revision: D3645303

ReactAndroid/src/main/java/com/facebook/react/flat/ImageRequestHelper.java

@@ -47,6 +47,7 @@ import com.facebook.imagepipeline.request.ImageRequestBuilder;
       source.startsWith("http://") ||
       source.startsWith("https://") ||
       source.startsWith("data:") ||
-      source.startsWith("file:///");
+      source.startsWith("file:///") ||
+      source.startsWith("content://");
   }
 }