Remove testing files from the project

[displague]

I ran into a few things when trying to terraform plan this:

• main.tf includes a TF Cloud backend that is specific to the testing environment. This file will prohibit users from consuming the module without modification. I think we should move the contents of this file to a secret and create it at test time:

  - name: Create testing backend config
    run: |
      echo $BACKEND_FILE >> backend.tf
    shell: bash
    env:
      BACKEND_FILE : ${{secrets.BACKEND_FILE}}

• OpenStack.tf could be main.tf (since the existing main.tf would become backend.tf)
• There is a root terraform.yml file which is nearly identical to the one in .github/, the one in the root adds terraform fmt and terraform plan
• terraform fmt applies a few changes to the project that should be included in the PR