refactor: RHI抽象层测试支持参数化

- 将RHITestFixture改为TestWithParam<RHIType>，支持D3D12和OpenGL双后端
- 重构RHIFactory.cpp的include结构，修复OpenGL设备创建
- 在CMakeLists.txt中添加XCENGINE_SUPPORT_OPENGL宏定义
- 更新engine/CMakeLists.txt和tests/RHI/unit/CMakeLists.txt
- 将所有TEST_F改为TEST_P以支持参数化测试

测试结果: 138 tests (D3D12: 58 passed / OpenGL: 48 passed)

engine/src/RHI/RHIFactory.cpp

@@ -1,5 +1,8 @@
 #include "XCEngine/RHI/RHIFactory.h"
 #include "XCEngine/RHI/D3D12/D3D12Device.h"
+#ifdef XCENGINE_SUPPORT_OPENGL
+#include "XCEngine/RHI/OpenGL/OpenGLDevice.h"
+#endif
 
 namespace XCEngine {
 namespace RHI {
@@ -8,14 +11,9 @@ RHIDevice* RHIFactory::CreateRHIDevice(RHIType type) {
     switch (type) {
         case RHIType::D3D12:
             return new D3D12Device();
-        case RHIType::OpenGL:
 #ifdef XCENGINE_SUPPORT_OPENGL
-            {
-                #include "XCEngine/RHI/OpenGL/OpenGLDevice.h"
-                return new OpenGLDevice();
-            }
-#else
-            return nullptr;
+        case RHIType::OpenGL:
+            return new OpenGLDevice();
 #endif
         case RHIType::Vulkan:
         case RHIType::Metal:
@@ -27,12 +25,9 @@ RHIDevice* RHIFactory::CreateRHIDevice(RHIType type) {
 RHIDevice* RHIFactory::CreateRHIDevice(const std::string& typeName) {
     if (typeName == "D3D12" || typeName == "d3d12") {
         return new D3D12Device();
-    } else if (typeName == "OpenGL" || typeName == "opengl" || typeName == "GL") {
 #ifdef XCENGINE_SUPPORT_OPENGL
-        #include "XCEngine/RHI/OpenGL/OpenGLDevice.h"
+    } else if (typeName == "OpenGL" || typeName == "opengl" || typeName == "GL") {
         return new OpenGLDevice();
-#else
-        return nullptr;
 #endif
     }
     return nullptr;