Infrastructure CI

As a reminder the commands to check the formatting and lint are,

terraform fmt --check=true
terraform validate

To have these run as part of CI i.e. for every change to the remote repository a .gitlab-ci.yml file placed in the root of the repository should contain,

infrastructure-ci:
  image: alpine:latest

  before_script:
  - apk update
  - apk add terraform
  - cd infrastructure
  - terraform init

  script:
  - terraform fmt --check=true
  - terraform validate

  only:
    changes:
      - infrastructure/**/*
      - .gitlab-ci.yml