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/CMakeLists.txt

@@ -292,3 +292,5 @@ if(MSVC)
 else()
     target_compile_options(XCEngine PRIVATE -Wall)
 endif()
+
+target_compile_definitions(XCEngine PRIVATE XCENGINE_SUPPORT_OPENGL)