Automate more of the tooling so that the first-time setup is easier.

[camjackson]

This requires more analysis to figure out what good looks like, but right now getting started with this code is too hard. There are two strategies:

1. Things should be done automatically where possible
2. If something is missing or wrong, you should be told what it is and how to fix it

Things that are manual and/or error prone right now:

• Installing terraform
• Installing the AWS CLI
• Configuring your AWS credentials
• Creating the bucket for the terraform state
• Configuring the terraform remote state
• Creating the Route53 hosted zone for the subdomain, and knowing its ID
• Setting up the variables needed for the terraform run (secrets, emails, IDs, etc)

Hopefully each of these can be made better by applying one or both of the strategies above.