tflint: Enable terraform_required_version rule

What does this MR do?

Enables the terraform_required_version rule to require that the terraform version be set on a module.

Notes:

• The GET docs state that TF 0.14 is the minimal version that is supported.
• AWS provider version was added

Terraform version constraint best practices: https://www.terraform.io/docs/language/expressions/version-constraints.html#best-practices

Author's checklist

When ready for review, the Author applies the workflowready for review label:

• Merge request:
  • Corresponding Issue raised and reviewed by the GET maintainers team.
  • Merge Request Title and Description are up to date, accurate, and descriptive
  • MR targeting the appropriate branch
  • MR has a green pipeline
• Code:
  • Check the area changed works as expected. Consider testing it in different environment sizes (1k,3k,10k,etc.).
  • Documentation created/updated in the same MR.
  • If this MR adds an optional configuration - check that all permutations continue to work.
  • For Terraform changes: setup a previous version environment, then run a terraform plan with your new changes and ensure nothing will be destroyed. If anything will be destroyed and this can't be avoided please add a comment to the current MR.
• Create any follow-up issue(s) to support the new feature across other supported cloud providers or advanced configurations. Create 1 issue for each provider/configuration. Contact the Quality Enablement team if unsure.