fix: RHI抽象层单元测试修复

- 实现 D3D12Device::CreateCommandQueue/CreateCommandList/CreateSwapChain
- 修复 Buffer::Map 对 DEFAULT heap 的问题 (Vertex/Index 使用 UPLOAD heap)
- 修复 Fence::IsSignaled() 初始值问题
- 修复 Sampler::GetNativeHandle() 返回值
- 修复 RHICapabilities 和 RHIDeviceInfo 初始化
- 修复 Shader 测试 (空 ShaderCompileDesc 预期)
- 修复 RHITestFixture 创建窗口句柄
- 重命名 opengl_engine_tests -> rhi_opengl_tests
- 添加 tests/RHI/unit/ 到构建系统

测试结果: 22 passed -> 59 passed

tests/RHI/OpenGL/unit/CMakeLists.txt

@@ -27,16 +27,16 @@ set(TEST_SOURCES
     test_sampler.cpp
 )
 
-add_executable(opengl_engine_tests ${TEST_SOURCES})
+add_executable(rhi_opengl_tests ${TEST_SOURCES})
 
-target_link_libraries(opengl_engine_tests PRIVATE
+target_link_libraries(rhi_opengl_tests PRIVATE
     opengl32
     XCEngine
     GTest::gtest
     GTest::gtest_main
 )
 
-target_include_directories(opengl_engine_tests PRIVATE
+target_include_directories(rhi_opengl_tests PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}/fixtures
     ${PROJECT_ROOT_DIR}/engine/include
     ${PROJECT_ROOT_DIR}/engine/src
@@ -44,4 +44,4 @@ target_include_directories(opengl_engine_tests PRIVATE
 
 enable_testing()
 include(GoogleTest)
-gtest_discover_tests(opengl_engine_tests)
+gtest_discover_tests(rhi_opengl_tests)