CI: Also test Windows + WDDM mode

[leofang]

#444 added a temporary Windows GPU runner with T4 so that we can finally start testing on Windows 🎉 However, it only runs on TCC mode and there is also WDDM mode that behaves differently (ex: TCC does not support mempools #206). Ideally we should test both and nvidia-smi allows a system to switch modes. WDDM mode is also important for applications that require handling of both graphics and compute.

However, after some desperate efforts (#461) I realized it is more complicated that just calling nvidia-smi inside the VM, because the default driver for data center GPUs like T4 do not support WDDM out of box. We need to install what's known as the "vGPU" driver to enable the switch, and vGPU is behind a paywall (license needed)...