d3d12: Add a debug flag for loading WinPixGpuCapturer.dll
This is useful for apps with launchers. For arm64, due to a PIX issue, it's the only way to get PIX attached to an x64 app with an x64 launcher.
This is useful for apps with launchers. For arm64, due to a PIX issue, it's the only way to get PIX attached to an x64 app with an x64 launcher.