Consider using virt-fw-vars to configure the UEFI variables

[rgl]

Consider using virt-fw-vars (from the virt-firmware project) instead of edk2-vars-generator. Using virt-fw-vars seems like we do not need to jump through so many hoops.

[stgraber]

That was on my todolist back when I was working on the LXD snap, so definitely something that'd still be great to do with the .deb :)

One thing I'd have to look at though is whether it makes it possible to modify the BootOrder variable easily. For the CSM firmware, we'd like the default nvram to have a BootOrder which starts with the entry of the built-in seabios.

With the current edk2-vars-generator, that's pretty straightforward as we can just run some EFI shell commands to setup the variable the way we want it.