Add Slurm script to pull containers

[jds485]

The build time to convert our container from docker to singularity on tallgrass is >10 mins and that's a lot to put on the login node. We should have a script that pulls the container we specify as an sbatch argument. Something like:

sbatch -A <account> get_container.slurm <container tag>

I'm not sure how feasible this is because we require "--docker-login" to the GitLab repo to pull the Docker container. We could submit this as an interactive job (if that's allowed on Tallgrass)