Having separate objects for validation results is unnecessary and overly
complicated at this point, and we should wait to introduce that kind of
complexity only when/if it's clearly needed.
[MAILPOET-4191]
We need to be able to validate an action in a workflow in the UI,
outside the context of a specific workflow run, so the validation can't
check things like the specific entities loaded in a subject.
[MAILPOET-4191]
