feat: refactor to modules and add ddos (#175)

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## Overview/Summary

Replacing the complete-multi-region starter module with a modular
implementation that leverages native Terraform inputs.

Also adding ddos plan and other minor fixes / improvements.

Please note that the `examples` folder and the `yaml.tf` file are
deleted by the ALZ PowerShell module, so they do not get pushed to
source control.

The purpose of the `yaml.tf` file is to enable us to spit out a config
YAML file that is used in the docs since we now use a tfvars files for
the local testing. See the sister PR for those files:
Azure/ALZ-PowerShell-Module#214

## This PR fixes/adds/changes/removes

N/A

### Breaking Changes

This is a breaking change to the complete-multi-region starter module.

## Testing Evidence

Please provide any testing evidence to show that your Pull Request
works/fixes as described and planned (include screenshots, if
appropriate).

## As part of this Pull Request I have

- [x] Checked for duplicate [Pull
Requests](https://github.com/Azure/alz-terraform-accelerator/pulls)
- [x] Associated it with relevant
[issues](https://github.com/Azure/alz-terraform-accelerator/issues), for
tracking and closure.
- [x] Ensured my code/branch is up-to-date with the latest changes in
the `main`
[branch](https://github.com/Azure/alz-terraform-accelerator/tree/main)
- [x] Performed testing and provided evidence.
- [x] Updated relevant and associated documentation.

.gitignore

@@ -30,7 +30,6 @@ override.tf.json
 # example: *tfplan*
 .terraform.lock.hcl
 terraform.log
-*.tfvars
 !terraform.tfvars
 templates/basic/terraform.tfvars
 templates/test_*

templates/complete_multi_region/README.md

@@ -0,0 +1,48 @@
+# Azure Landing Zones Accelerator Starter Module for Terraform - Complete Multi-Region
+
+This module is part of the Azure Landing Zones Accelerator solution. It is a complete multi-region implementation of the Azure Landing Zones Platform Landing Zone for Terraform.
+
+It deploys a hub and spoke virtual network or Virtual WAN architecture across multiple regions.
+
+The module deploys the following resources:
+
+- Management group hierarchy
+- Azure Policy definitions and assignments
+- Role definitions
+- Management resources, including Log Analytics workspace and Automation account
+- Hub and spoke virtual network or Virtual WAN architecture across multiple regions
+- DDOS protection plan
+- Private DNS zones
+
+## Usage
+
+The module is intended to be used with the [Azure Landing Zones Accelerator](https://aka.ms/alz/accelerator/docs). Head over there to get started.
+
+>NOTE: The module can be used independently if needed. Example tfvars files can be found in the `examples` directory for that use case.
+
+### Running Directly
+
+#### Run the local examples
+
+Create a `terraform.tfvars` file in the root of the module directory with the following content, replacing the placeholders with the actual values:
+
+```hcl
+starter_locations            = ["uksouth", "ukwest"]
+subscription_id_connectivity = "00000000-0000-0000-0000-000000000000"
+subscription_id_identity     = "00000000-0000-0000-0000-000000000000"
+subscription_id_management   = "00000000-0000-0000-0000-000000000000"
+```
+
+##### Hub and Spoke Virtual Networks Multi Region
+
+```powershell
+terraform init
+terraform apply -var-file ./examples/config-hub-and-spoke-virtual-networks-multi-region.tfvars
+```
+
+##### Virtual WAN Multi Region
+
+```powershell
+terraform init
+terraform apply -var-file ./examples/config-virtual-wan-multi-region.tfvars
+```