fix: D3D12 CommandQueue and SwapChain unit test fixes

- CommandQueue::ExecuteCommandLists: fix type conversion from void** to ID3D12CommandList**, reset command list before execution, add null checks
- SwapChain::ShouldClose: add m_shouldClose member and implement getter/setter
- SwapChain::SetFullscreen: add m_fullscreen member to track state locally

engine/include/XCEngine/RHI/D3D12/D3D12SwapChain.h

@@ -45,6 +45,8 @@ private:
     uint32_t m_height;
     uint32_t m_bufferCount;
     std::vector<D3D12Texture> m_backBuffers;
+    bool m_shouldClose = false;
+    bool m_fullscreen = false;
 };
 
 } // namespace RHI