Upsell the GitLab Managed Terraform state if the repo contains `.tf` files

Upsell the GitLab Managed Terraform state if the repo contains .tf files

Provide a nice info banner that can be declined by project.

Proposal

1. User opens a GitLab project with .hcl files (HCL files are used most of the time for Terraform)
2. We show a banner at the top of the page to learn more about our Terraform features. Example: https://gitlab.com/gitlab-org/gitlab/uploads/fd4880a2161a3656f49548edfa5825fc/image.png
3. The user either clicks on the call to action button or dismisses the banner

Design inspiration in the linked issue

Header: "Using Terraform? Try the GitLab Managed Terraform State"

Text: The GitLab managed Terraform state backend can store your Terraform state easily and securely, and spares you from setting up additional remote resources. Its features include: versioning, encryption of the state file both in transit and at rest, locking, and remote Terraform plan/apply execution.

Button: Learn more about GitLab's Backend State, Link: https://docs.gitlab.com/ee/user/infrastructure/terraform_state.html