Use Overlay alert on iOS to address flakiness in CI (#6186)

* Use Overlay alert on iOS to address flakiness in CI

playground/src/app.js

 const testIDs = require('./testIDs');
 const Screens = require('./screens/Screens');
 
-if (Platform.OS === 'android') {
-  alert = (title, message) => Navigation.showOverlay({
-    component: {
-      name: Screens.Alert,
-      passProps: {
-        title,
-        message
-      }
+// @ts-ignore
+alert = (title, message) => Navigation.showOverlay({
+  component: {
+    name: Screens.Alert,
+    passProps: {
+      title,
+      message
     }
-  });
-};
+  }
+});
 
 function start() {
   registerScreens();

playground/src/screens/LifecycleScreen.js

   push = () => Navigation.push(this, Screens.Pushed);
   screenPoppedEvent = async () => {
     this.showUnmountAndDisappearAlerts = false;
-    const unregister = Navigation.events().registerScreenPoppedListener((event) => {
-      alert('Screen popped event')
-      unregister.remove();
+    const promise = new Promise((resolve) => {
+      const unregister = Navigation.events().registerScreenPoppedListener((event) => {
+        alert('Screen popped event');
+        unregister.remove();
+        resolve();
+      });
     });
-    await Navigation.pop(this);
+    await Promise.all([Navigation.pop(this), promise]);
   }
   pop = () => Navigation.pop(this);
   dismiss = () => Navigation.dismissModal(this);