refactor: 删除旧的RHI实现，添加D3D12测试用例和第二阶段计划

engine/src/RHI/D3D12/D3D12Shader.cpp

@@ -1,40 +0,0 @@
-#include <Rendering\Shader.h>
-#include <d3dcompiler.h>
-#include <wrl/client.h>
-#include <string>
-
-namespace XCEngine {
-namespace RHI {
-
-bool CompileShader(const char* filePath, const char* entryPoint, const char* target, ShaderBytecode& outBytecode) {
-    UINT flags = D3DCOMPILE_DEBUG | D3DCOMPILE_SKIP_OPTIMIZATION;
-    
-    ID3DBlob* shaderBuffer = nullptr;
-    ID3DBlob* errorBuffer = nullptr;
-    
-    HRESULT hr = D3DCompileFromFile(
-        std::wstring(filePath, filePath + strlen(filePath)).c_str(),
-        nullptr,
-        nullptr,
-        entryPoint,
-        target,
-        flags,
-        0,
-        &shaderBuffer,
-        &errorBuffer);
-    
-    if (FAILED(hr)) {
-        if (errorBuffer) {
-            OutputDebugStringA((const char*)errorBuffer->GetBufferPointer());
-            errorBuffer->Release();
-        }
-        return false;
-    }
-    
-    outBytecode.bytecode = shaderBuffer->GetBufferPointer();
-    outBytecode.size = shaderBuffer->GetBufferSize();
-    return true;
-}
-
-} // namespace RHI
-} // namespace XCEngine