automate consul backups

[Ardiea]

Description/Context

During the course of https://github.com/mitodl/ol-infrastructure/issues/2518 I got to thinking of how to best do these migrations / upgrade for consul clusters in a safe manner. It occurs to me we should have an automated consul backup solution similar to our vault solution.

https://developer.hashicorp.com/consul/tutorials/operate-consul/backup-and-restore

Plan/Design