LibGL+LibGPU+LibSoftGPU: Implement matrix stack per texture unit

Each texture unit now has its own texture transformation matrix stack.
Introduce a new texture unit configuration that is synced when changed.
Because we're no longer passing a silly `Vector` when drawing each
primitive, this results in a slightly improved frames per second :^)

Userland/Libraries/LibGPU/StencilConfiguration.h

@@ -6,7 +6,6 @@
 
 #pragma once
 
-#include <LibGPU/Config.h>
 #include <LibGPU/Enums.h>
 
 namespace GPU {