let betterRenderer import the modules

The module file set moves to its own eu07_modules library: a target can
only consume C++20 modules by linking the target that owns them, and
betterRenderer is a separate add_library. Its project includes become
imports.

CXX_EXTENSIONS must match across the two - a BMI built with -std=c++20
is refused by a unit compiled with -std=gnu++20.

betterRenderer/renderer/source/track_batching.cpp

@@ -4,9 +4,9 @@
 #include "nvrenderer/nvrenderer.h"
 #include "nvrendererbackend.h"
 
-#include <utilities/Timer.h>
-#include <model/AnimModel.h>
-#include <simulation/simulation.h>
+import eu07.utilities.timer;
+import eu07.simcore;
+import eu07.simulation.simulation;
 
 namespace BatchingUtils {