Build the VirtualBox image with the qemu builder and convert it

Fix #108
6 jobs for qemu-virtualbox in 17 minutes and 53 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Lint
passed shellcheck #2858

00:00:23

passed shfmt #2859

00:00:16

passed validate-packer #2860

00:02:02

 
  Build
passed build:cloud-qemu #2861
ipv6

00:15:49

passed build:vagrant-qemu #2863
ipv6

00:14:23

passed build:vagrant-virtualbox #2862
ipv6

00:13:12