More Robust generation

[korewaChino]

Right now our appstream generation is kinda... scuffed.

Current tools are kind of hard to trace and use, upstream appstream expects your repo layout to be like Debian, the current GLib implementation we use is dead.

So we need to create a more robust solution, maybe using https://bilelmoussaoui.github.io/appstream/appstream/ or if upstream AppStream exposes a binding somewhere else that's not C++. Hopefully in Python.

more references:

https://crates.io/crates/libappstream
https://github.com/ximion/appstream