No app icon for AppImage on Linux (Version 1.40.0 (Beta))

[kittaakos]

Bug Description:

The app icon on Linux is missing. It's a regression for #180. The backend webpacking was the breaking change. It works downstream; thanks for the great example 🙌

no_app_icon_appimage_linux.mp4

Steps to Reproduce:

1. Open the AppImage 1.40.0 on Linux
2. No app icon

Additional Information

• Operating System: Ubuntu 22.04
• Theia Version: 1.40