[Optimisation] Reduce the flatpak size as much as possible

[cappsyco]

The Flatpak is currently 122MB!

The reasons for this are most likely to do with the following:

• The applet and settings app are not compiled together as this causes massive performance issues in the applet. This is likely leading to many duplicated dependencies
• The applet is built with many distro logos at compile time

Possible solutions

• Figuring out the combined compiling to prevent the applet's issues
• Waiting for the settings app to no longer be needed (when integration into the main Settings app is available)
• Reduce the number of default distro logos to just the most likely ones that will be used (combined with support for adding custom files)
• Any compression that can be done on the logo SVGs (probably minimal but worth a look)