Add option for enabling nested virtualization

[Fabiosilvero]

What feature do you want to see added?

Hello team !

We use Android QEMU device for automated tests, and we would like to, instead of using a custom GCE image with the licence key for nested virtualization, simply have a boolean to enable it, to avoid maintaining 2 images nearly identical.

Example :

enable_nested_virtualization: true

google compute instances create command seems to support it :

gcloud compute instances create VM_NAME \
  --enable-nested-virtualization \
  --zone=ZONE \
  --min-cpu-platform="Intel Haswell"

See Google doc.

Thanks and have a good day !

Upstream changes

No response