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