WorkflowConditions should return a WorkflowConditionOutput that contains failReasons

The WorkflowConditions associated with a task currently only return true or false. While this has sufficed in the past, there really should be some sort of formal data structure (i.e. my "WorkflowConditionOutput" suggestion) that contains, at a minimum:

1. WorkflowCondition success, true or false
2. List<FailureReason> which contains a (list of) reason(s) why the condition failed
3. Metadata object representing the dynMetadata passed in to the WorkflowCondition (that it used to evaluate)