Ability to support Terraform input variables

[lucasfcosta]

• Allow passing tfvars file in the CLI
• Allow passing passing individual vars
• Support all input modes Terraform does (double check)
• Duplicate names -> Allow terraform to error out (default behaviour)
• Use terraform.tfvars by default (from cwd)

[vieiralucas]

https://developer.hashicorp.com/terraform/language/values/variables#assigning-values-to-root-module-variables