Create vagrant setup for testing installability

briar-desktop/build.gradle.kts

vagrant/.gitignore

vagrant/debian-bullseye/README.md

vagrant/debian-bullseye/Vagrantfile

vagrant/debian-bullseye/bootstrap.sh

vagrant/ubuntu-bionic/README.md

vagrant/ubuntu-bionic/Vagrantfile

vagrant/ubuntu-bionic/bootstrap.sh

vagrant/ubuntu-focal/README.md

vagrant/ubuntu-focal/Vagrantfile

vagrant/ubuntu-focal/bootstrap.sh

vagrant/ubuntu-jammy/README.md

vagrant/ubuntu-jammy/Vagrantfile

vagrant/ubuntu-jammy/bootstrap.sh