Magic Module - Terraform Samples PR : How to use tftools for PR validations?

# Testing https://github.com/GoogleCloudPlatform/magic-modules/pull/5448/files


# Step by Step - Instructions

- Step1: Download files
   
   ```
wget https://github.com/GoogleCloudPlatform/magic-modules/raw/e8d547a02b95d7a1a650b52c5968404ee57a7b14/mmv1/products/compute/terraform.yaml
wget https://github.com/GoogleCloudPlatform/magic-modules/raw/e8d547a02b95d7a1a650b52c5968404ee57a7b14/mmv1/templates/terraform/examples/external_ssl_proxy_lb_mig_backend_custom_header.tf.erb
   ```

- Step2: Using Gcloud shell

   Install & use `tftools` from https://github.com/GoogleCloudPlatform/terraform-sample-tools/tree/main/tools/Magic%20Modules%20-%20Terraform%20Automation%20Tools

   After git clone of above repo, do following in `terraform-sample-tools/tools/Magic Modules - Terraform Automation Tools/`
   ```
sudo python3 setup.py install
   ```

- Step3: Prepare terraform executable script

  ```bash
tftools external_ssl_proxy_lb_mig_backend_custom_header.tf.erb terraform.yaml
  ```
This tftools is installed in step 2. Using this tools, we run some pre-check validation on config & erb files and then generates a terraform file. In this we should get `external_ssl_proxy_lb_mig_backend_custom_header.tf`

- Step4: Run terraform init & validation

  ```bash
terraform init
terraform validate
  ```
If `Success` is reported for validate proceed to next steps

- Step5: Terraform Apply to create & run the infra

  ```bash
terraform apply
  ```

- Step6: Terraform detroy to rollback infra setup

  ```bash
terraform destroy
  ```