Investigate updating GenerateThreadedSystems to not require running through Godot (might be possible with Godot 4)

[hhyyrylainen]

As the simple tests can run and load the thrive library, I think it might be possible to convert that one script to not require running it through Godot. One tricky part is to determine if it is fine for the Scripts project to depend directly on the Thrive project or if another approach is needed (like dynamically loading).

If it is updated need to update the documentation: https://github.com/Revolutionary-Games/Thrive/blob/master/doc/architecture.md#simulation-multithreading