Create New Skeleton "skeleton-tf-root-module"

# 💡 Summary #

Consider creating a new skeleton repository that either descends from [cisagov/skeleton-generic](https://github.com/cisagov/skeleton-generic) or from this repo. This would focus on Terraform code that is not designed for reuse as opposed to the goal of this skeleton.

## Motivation and context ##

We have been using this skeleton for anything Terraform related and it has worked, but the workflows for Terraform modules and Terraform deployments have core differences. Creating a new `skeleton-tf-root-module` repository would allow Terraform deployment related standards to be represented in a skeleton instead of needing to look across existing deployment repositories to figure out what files need to be added (at minimum) as well as how things look across such projects in our organization.

## Implementation notes ##

Ideally once this new skeleton is created we would, over time, migrate any Terraform code repositories that are not designed to be importable modules to descend from this new skeleton. Then any future Terraform with similar design goals would start from the new skeleton instead of this repository.

## Acceptance criteria ##

- [ ] New repository is created
- [ ] Dev team signs off on the Initial Commits Pull Request
- [ ] (OPTIONAL) Existing Terraform deployment repositories are migrated to use this new skeleton

Start by comparing cisagov/skeleton-generic with this repository and review existing Terraform deployment repositories to identify the standards and minimum files the new skeleton should represent. Define the new skeleton-tf-root-module repository and prepare its Initial Commits Pull Request for Dev team sign-off. Treat migration of existing repositories as optional scope.

Written by the indexing model from the issue text.