SNFR7 - Idempotency Tests

Modules MUST implement idempotency end-to-end (deployment) testing. E.g. deploying the module twice over the top of itself.

Modules SHOULD pass the idempotency test, as we are aware that there are some exceptions where they may fail as a false-positive or legitimate cases where a resource cannot be idempotent.

For example, Virtual Machine Image names must be unique on each resource creation/update.