Zero-dependency AppImage support | Current state of the AppImage

[realmazharhussain]

Current implementation of the GDM Settings' AppImage is inadequate and hacked together. See #208, #196, #147, #137, etc.

The AppImage is leaky. It, sometimes, tries to load shared libraries from the host system which obviously fails due to mismatched library versions. Most likely, the AppImage cannot even be built on setups other than mine.

So, the AppImage build system/scripts need a complete revamp. They should

• be portable i.e. we should be able to build the AppImage on setups other than mine e.g. a CI/CD pipeline
• have a Zapps-like approach where everything needed by the app, including GLibC, is bundled inside the AppImage and no shared lib or binary from outside the AppDir is ever loaded/executed during runtime.