Finish SplahActivity if react context exists

Fixes #1938 Closes #1900

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

 
         if (NavigationApplication.instance.getReactGateway().hasStartedCreatingContext()) {
             NavigationApplication.instance.getEventEmitter().sendAppLaunchedEvent();
+            if (NavigationApplication.instance.clearHostOnActivityDestroy()) {
+                overridePendingTransition(0, 0);
+                finish();
+            }
             return;
         }