docker-images: Add ignite-ubuntu

Created by: efritz

Verified to work when the image is created locally on the compute node containing firecracker.

docker build -t ignite-ubuntu-local .
sudo ignite create ignite-ubuntu-local --name test --cpus 1 --memory 1GB --size 4GB --ssh --runtime docker
sudo ignite test
sudo ignite exec test "docker run sourcegraph/lsif-go lsif-go -h"