build VirtualBox images with Vagrant (or similar) instead of manually

The manual VirtualBox image build is well-documented, but because it's manual, it's time-consuming and hard to keep up to date.

This issue is to convert the manual steps to something automated, such as Vagrant or Packer. @mej has a Vagrant Gist to start from: https://gist.github.com/mej/bdb1c1c6abe2632e8d88a22ee3b5af81

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information