Terraform State verification

BitOps is not aware of Terraform State, so if an operations repo is deployed without one, Bitops will deploy all new resources.
- Add a check for S3 backend configuration.
- Add a check for local state file in the operations repo.
- Reject if none of the above exists.

Start by locating BitOps' Terraform deployment and operations-repository validation entry points, then trace how backend configuration and local state are currently handled. Verify the checks for an S3 backend and a local state file, and confirm that deployment is rejected when neither exists.

Written by the indexing model from the issue text.