add native module overriding

Differential Revision: D2700638

fb-gh-sync-id: a88ffaf864be848e1bba22e443d301e4623f04ec

ReactAndroid/src/main/java/com/facebook/react/bridge/BaseJavaModule.java

@@ -327,6 +327,11 @@ public abstract class BaseJavaModule implements NativeModule {
     // do nothing
   }
 
+  @Override
+  public boolean canOverrideExistingModule() {
+    return false;
+  }
+
   @Override
   public void onCatalystInstanceDestroy() {
     // do nothing