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.