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/nvrendererbackend.cpp

@@ -1,6 +1,6 @@
 #include "nvrendererbackend.h"
 
-#include "utilities/Logs.h"
+import eu07.utilities.logs;
 #include <fmt/format.h>
 
 void NvRendererMessageCallback::message(nvrhi::MessageSeverity severity,