Upgrading libvirtxml to libvirt.org/go/libvirtxml, which is where development will happen going forward (the original repo has been archived)
Making use of go run when running packer-sdc, which avoids needing a local install of the binary at a matching version (since go-run will use packer-sdc at the version defined in the go.mod)
This PR includes some small cleanups, namely: