PR review flow integration: Terraform plan + Ansible dry-run

This is a good time and repository to show the PR flow with BitOps.
https://github.com/bitovi/bitops/issues/325

When using this GH Action, on every PR the terraform should run plan, and ansible should run dry-run,
show the result as a GH Status check.
Once the PR is approved and merged, - run the actual terraform apply.

Bonus points if we could post the `tf plan` diff back to the PR as a comment.

See https://github.com/marketplace/actions/terraform-pr-commenter#screenshots as an example:

StackStorm is a complex beast and allowing users to run the proper PR review flow instead of "I'm feeling lucky" `apply` would prevent users from shooting themselves in the foot and encourage best practices.

Start at the repository's GitHub Action entry point and trace how Terraform and Ansible deployment runs are invoked. Define the PR flow around Terraform plan, Ansible dry-run, GitHub status checks, and apply after merge; the optional Terraform diff comment is additional scope. Done means the workflow safely distinguishes review runs from merged deployment runs.

Scritto dal modello di indicizzazione a partire dal testo della issue.