Add better support for Terraform/Tofu destroy

We are having issues with the way Terraform/Tofu destroy lifecycle is handled.

Currently there are two ways to run a destroy for one of these stacks:

1. Run a task where you manually type in “terraform destroy -auto-approve”

2. Delete the stack and select the option to destroy resources managed by the stack

Both of these methods have some obvious downsides:

Tasks are not intuitive for operational users of Spacelift that don’t commonly destroy stacks. Destroy lifecycle hooks are not executed as part of tasks so the destroy process may fail or be incomplete when run with a task.

Deleting the stack doesn’t support all use cases. In some cases we want to destroy the resources managed by a stack but not the stack itself. We use the stack to create resources again using the same configuration later.

Most importantly:

both methods to not provide a way for us to review the destroy plan and choose to confirm or reject the destroy. There are many reasons a destroy plan may not be acceptable and the underlying project may need unexpected changes before proceeding.

Spacelift already has a nice UX for other parts of the TF lifecycle. We would like to option to trigger a destroy, where the destroy lifecycle is executed with hooks and all, and where we get the opportunity to review the destroy plan and confirm or reject it.