Resolves https://github.com/dagster-io/dagster/issues/2378.
Here, we write a Helm hook to initiate dagster instance migrate in a kubernetes
job, to occur after all resources have been loaded or updated in kubernetes via
helm install or helm upgrade.
See:
https://helm.sh/docs/topics/charts_hooks/
https://itnext.io/database-migrations-on-kubernetes-using-helm-hooks-fb80c0d97805
https://medium.com/flant-com/custom-commands-deploying-in-kubernetes-df4ea4487f18