feat: Enhance GUI rendering and configuration management

- Added support for FreeType font rendering in GuiRenderer, including glyph loading and text rendering capabilities.
- Introduced GuiFontConfig structure to manage font settings through configuration.
- Updated JsonConfigService to parse and provide GUI font settings from JSON configuration.
- Implemented MaterialX shader generation capabilities with a new MaterialXShaderGenerator class.
- Enhanced ShaderScriptService to utilize MaterialX for shader generation based on configuration.
- Added NullGuiService as a placeholder implementation for GUI service.
- Extended IConfigService interface to include methods for retrieving graphics backend, MaterialX, and GUI font configurations.
- Updated RuntimeConfig structure to include graphics backend and MaterialX configurations.
- Added tests to ensure proper integration of new configuration settings and shader generation functionality.

tests/test_cube_script.cpp

@@ -2,6 +2,7 @@
 #include "services/impl/script_engine_service.hpp"
 #include "services/impl/scene_script_service.hpp"
 #include "services/impl/shader_script_service.hpp"
+#include "services/interfaces/i_config_service.hpp"
 
 #include <array>
 #include <cmath>
@@ -68,7 +69,8 @@ int main() {
         engineService->Initialize();
 
         sdl3cpp::services::impl::SceneScriptService sceneService(engineService, logger);
-        sdl3cpp::services::impl::ShaderScriptService shaderService(engineService, logger);
+        std::shared_ptr<sdl3cpp::services::IConfigService> configService;
+        sdl3cpp::services::impl::ShaderScriptService shaderService(engineService, configService, logger);
 
         auto objects = sceneService.LoadSceneObjects();
         Assert(objects.size() == 1, "expected exactly one scene object", failures);