Distinguish workflow transition based emails by workflow

Right now, all email events derived from order workflows are placed into a single group keyed by transition ID. This is nice in the sense that if multiple workflows use the same transition ID, any order transitioning through the same step will activate the email. However, it also makes it impossible to differentiate emails (or not send emails) for one workflow's implementation of the transition vs. another's.

We do have the workflow ID in the WorkflowTransitionEvent object, so it would be possible for us to refine our approach. This would mean keying by both the workflow ID and the transition ID with an upgrade path if at all possible. The grouping would then need to be updated to separate these email events by workflow with appropriate labels.