Introduce "Remote Viewer mode"
Submitted by Felipe Borges
Since we aim to suit both virtualization and remote connection users, we should be able to build and launch Boxes with remote viewing capabilities only.
This way remote viewing users don't need to have a working virtualization stack underneath Boxes.
It would also make it easier to run Boxes within a flatpak since what's currently blocking us in this front is the presence/access to libvirt in the sandbox.