Add the ability to reference a step chain from a workflow

Currently when a step chain is added to a workflow, it is copied into the workflow. Any changes made to the step chain will not be picked up unless the step chain is replaced in the workflow by the updated version. This is a request to add the ability to reference a step chain from a workflow. The step chain is not copied into the workflow, so changes to the step chain will be picked up without a change to the workflow.