add support for CreateWorkflowInstanceWithResult

[pedesen]

I think there are 3 options to make that work:

• extend "create wfi" node to output the outcome of the workflow when it has finished
• create an additional "create wfi w/ result" node which only outputs when the workflow has finished
• create a "workflow completed" node, which outputs each time any workflow finishes

More info: https://zeebe.io/blog/2019/10/0.22-awaitable-outcomes/