Wait for external event quickstart tutorial for Dapr Workflows

## Describe the feature
It would be good to have a variation workflows that makes use of the wait-for external event capability to showcase how it is used in conjunction with another building block API

ADDED Support for suspending, resuming, and raising events to workflows [1052](https://github.com/dapr/dotnet-sdk/issues/1052)

https://docs.dapr.io/developing-applications/building-blocks/workflow/workflow-features-concepts/#:~:text=Workflows%20can%20create%20%E2%80%9Cwait%20for,which%20next%20steps%20to%20take.