This allows Boxes to boot EFI systems even when secure-boot is not
supported by the environment.

With this, users should be able to run GNOME OS and (soon) other
EFI-only systems in the distro-packaged version of Boxes of their
choice.

While the Flatpak version of Boxes currently handles well secure-boot,
distros have not. Just a few distros support EFI and provide the
proper environment for the virt stack that Boxes needs to boot EFI
VMs consistently.

The distro-packaged version of Boxes runs without the constrains
of the Flatpak sandbox, and can provide additional (useful) features
such as USB redirection, Network Bridge, etc...