Enforce version constraints for command options

For each option, check what Terraform version it was added in, and add a `tf.compatible` check enforcing the minimum version. We might want a better framework for doing this than adding logic in each command, but it might not be worth doing that because option compatibility is per command, not per option, and often influences default flag behaviour (see the changes in https://github.com/hashicorp/terraform-exec/pull/120 for an example).