Update CMake configuration and CI workflows for improved compatibility and testing

- Updated minimum CMake version requirement from 3.5 to 3.16 to leverage new features and policies.
- Enhanced CI workflows to include additional build configurations for Ubuntu and macOS, improving cross-platform support.
- Added conditional linking for ImGui Test Engine in the CMakeLists, allowing for UI testing when enabled.
- Refactored CMake commands in CI to ensure consistent policy version handling and streamlined build processes.
- Introduced new constructors for MenuItem in the GUI to enhance menu item management and flexibility.

src/app/core/window.cc

@@ -75,7 +75,9 @@ absl::Status ShutdownWindow(Window& window) {
   SDL_CloseAudioDevice(window.audio_device_);
   
   // Stop test engine WHILE ImGui context is still valid
+#ifdef YAZE_ENABLE_IMGUI_TEST_ENGINE
   test::TestManager::Get().StopUITesting();
+#endif
   
   // Shutdown ImGui implementations
   ImGui_ImplSDL2_Shutdown();
@@ -85,7 +87,9 @@ absl::Status ShutdownWindow(Window& window) {
   ImGui::DestroyContext();
   
   // NOW destroy test engine context (after ImGui context is destroyed)
+#ifdef YAZE_ENABLE_IMGUI_TEST_ENGINE
   test::TestManager::Get().DestroyUITestingContext();
+#endif
   
   // Shutdown graphics arena BEFORE destroying SDL contexts
   gfx::Arena::Get().Shutdown();