Geo: Self Service Framework - Verify terraform states

Background

With &1817 (closed) complete, we need to add verification for the other blob types! This issue is for adding it to Terraform States.

Definition of Done

• Terraform state blobs are verified
• Verification for terraform states is enabled and tested on staging
• An issue is filed to coordinate the feature flag release

Procedure

Loosely From @mkozono on &5285 (comment 495424992)

1. Add primary-side verification fields to all Blob model tables
2. Add secondary-side verification fields to all Blob registry tables
3. Return the status of Feature.enabled?(:geo_terraform_state_verification), from self.verification_feature_flag_enabled? for all blobs (except package files which should always return true)
4. Add to all Blob registry classes:

   include ::Gitlab::Geo::VerificationState
   include ::Geo::VerifiableRegistry

5. Test verification
6. Enable on staging, test with GitLab Environment Toolkit
7. Remove FF geo_terraform_state_verification