--appimage-extract and other runtime options don't work when using external runtime

[TheAssassin]

I noticed that some runtime functionalities like --appimage-extract don't work as intended with an external runtime.

The use case of using a custom, separate runtime to run existing AppImages isn't very well tested and needs to be improved. Otherwise, users of AppImageLauncher cannot extract AppImages.

[probonopd]

Why does AppImageLauncher need an external runtime?

[TheAssassin]

@probonopd you should maybe bookmark this link: https://github.com/TheAssassin/AppImageLauncher/blob/dbdc1b22ed3e5d0b228a5d5b7f935937cc6ed9c8/src/main.cpp#L58-L63

[TheAssassin]

Going to work on this next.