BREAKING CHANGES: We remove the dependency on the deprecated `hashicorp/template` provider and use the Terraform built in `templatefile` function. This will broke some workflows due to previously being able to pass in the raw contents of a template file for processing. The `templatefile` function requires a template file that exists before running a plan.
NOTES: The EKS cluster can be provisioned with both private and public subnets. But Fargate only accepts private ones. This new variable allows to override the subnets to explicitly pass the private subnets to Fargate and work around that issue.
