add EFI boot support for VM creation --vmfile --efi

[adrelanos]

When using --vmfile I don't think it is currently possible to combine it with --efi device. (What would be the device?)

Could you please add support for creating EFI boot enabled VMs?

EFI boot is supported by KVM, Xen, VirtualBox, VMware and possibly others.

[mika]

I'm not objecting to adding support EFI support for VM creation, but e.g. QEMU/KVM requires a separate efi disk (-efidisk0 ....) whereas the VMs as used in VirtualBox don't require such an extra disk, so it's not entirely trivial.

If anyone wants to work on this, I'd be more than happy to accept PRs, but I probably won't have time to work on this in my spare time.