Fix react-native-youtube support (#6220)

Support for the react-native-youtube package was added in #5999 but due to a faulty merge it wasn't complete.

Fixes #6214

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/navigator/Navigator.java

 package com.reactnativenavigation.viewcontrollers.navigator;
 
 import android.app.Activity;
+import android.view.View;
 import android.view.ViewGroup;
 
 import com.facebook.react.ReactInstanceManager;
     public void setContentLayout(ViewGroup contentLayout) {
         this.contentLayout = contentLayout;
         contentLayout.addView(rootLayout);
-        contentLayout.addView(modalsLayout);
-        contentLayout.addView(overlaysLayout);
+        modalsLayout.setVisibility(View.GONE); contentLayout.addView(modalsLayout);
+        overlaysLayout.setVisibility(View.GONE); contentLayout.addView(overlaysLayout);
     }
 
     public Navigator(final Activity activity, ChildControllersRegistry childRegistry, ModalStack modalStack, OverlayManager overlayManager, RootPresenter rootPresenter) {

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/navigator/NavigatorTest.java

         uut.setContentLayout(contentLayout);
     }
 
+    @Test
+    public void setContentLayout_modalAndOverlayLayoutsAreGONE() {
+        ViewGroup contentLayout = Mockito.mock(ViewGroup.class);
+        uut.setContentLayout(contentLayout);
+        assertThat(uut.getModalsLayout().getVisibility()).isEqualTo(View.GONE);
+        assertThat(uut.getOverlaysLayout().getVisibility()).isEqualTo(View.GONE);
+    }
+
     @Test
     public void bindViews() {
         verify(rootPresenter).setRootContainer(uut.getRootLayout());