Adding "-auto-approve" as an optional flag to the SDK.

Hi all,
I’ve observed that most Terraform operations are run with `-auto-approve` by default, so there isn’t always an opportunity to review the resources that will be created or destroyed. Do you think it would be useful to add support in the SDK for reviewing changes before they’re applied?

Ref: https://github.com/hashicorp/terraform-exec/blob/7ae12dd2176573ec55c9b5c84542d1b466efce54/tfexec/apply.go#L176

Thanks!

Start with the referenced apply.go location and review how the SDK currently handles Terraform apply options. Confirm the intended optional -auto-approve behavior and how review-before-apply should work; done means callers can choose whether approval is required when applying changes.

Written by the indexing model from the issue text.