Auto-update add-ons

This category of add-ons (for now: AI-related add-ons) will be installed in a new, separate folder: “Auto-Updated Add-Ons”, instead of the regular Add-Ons folder. This allows for automatically checking for updates and, when applicable, updating these add-ons each time the app is restarted, without any user interaction. The Add-on Manager lists these add-ons just like other ones, and displays the version number.