QDS-11236 Simple caching method for the demos

This MR brings the following features;

• add: a simple caching method for the examples
• add: remove button for cached examples
• add: show a warning to the user if something goes wrong when opening/running the project
• add: enhance the performance by clearing the qmlengine cache and resetting it each time when a new project is running
• chore: bumps the app version to 14

android/AndroidManifest.xml

 <?xml version="1.0"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="io.qt.qtdesignviewer"
-    android:installLocation="auto" android:versionCode="13" android:versionName="1.2">
+    android:installLocation="auto" android:versionCode="14" android:versionName="1.2">
     <!-- %%INSERT_PERMISSIONS -->
     <!-- %%INSERT_FEATURES -->
     <supports-screens android:anyDensity="true" android:largeScreens="true"