Migrate CloudFormation to Terraform

[cyramic]

While this will definitely be tricky to pull off, there's every reason to do this

• CloudFormation has been stated by AWS support to be the inferior way to do IaC, and that terraform should be used instead
• Terraform is more scalable and understood by a wider audience
• Terraform has more features to allow some of the more complex aspects of deployment to be automated
  • Lambda functions can be automated in zipping and uploading code changes
  • Some functions in the infrastructure have no way to be defined in IaC from what I could find (e.g. certificate manager, some attributes in EC2, sharing values across stacks, etc)
• Terraform has the import operation which means this transition could potentially be seamless.
• Terraform is understood by more people on the team.

[cyramic]

Set as "really nice to have" but the effort involved means that it isn't a priority at the moment. It may become an issue later if we wish to scale or automate further.