add related infra into run/infra

Other than domains, which are managed by gliderlabs/infra.gl, and the cluster(s) it runs on, infrastructure for Cmd should be defined by Terraform and put in run/infra. For now this is just the several CloudFront distributions recently created for SSL. They'll depend on certificates, but TF won't manage these. I believe it has them as a data provider resource so we can at least reference them and ensure they exist.

CircleCI will need a step similar to gliderlabs/infra.gl to apply changes.