Return if hasStartedCreatingContext already in SplashActivity (#701)

android/app/src/main/java/com/reactnativenavigation/controllers/SplashActivity.java

 
         if (NavigationApplication.instance.getReactGateway().hasStartedCreatingContext()) {
             finish();
+            return;
         }
 
         if (ReactDevPermission.shouldAskPermission()) {