Add plugin and host registration to multiple_flutters example (#942)

add_to_app/multiple_flutters/multiple_flutters_android/app/src/main/AndroidManifest.xml

@@ -2,6 +2,14 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="dev.flutter.multipleflutters">
 
+    <!-- Provide required visibility configuration for API level 30 and above -->
+    <queries>
+        <intent>
+            <action android:name="android.intent.action.VIEW" />
+            <data android:scheme="https" />
+        </intent>
+    </queries>
+
     <application
         android:name=".App"
         android:allowBackup="true"