[Scenario]: Async pattern for long-running api calls

### Describe the scenario

Add an async flow where a Durable Azure Function is called to provide async functionality to return immediately to the caller a 202, and then process the request in another thread that uses a callback when complete

### Improvement to Project

The forward-request policy has a 'hard-limit' timeout of 240 seconds, so there are times when you might have longer running apis that need a pattern to use to successfully respond in a timely manner. Showing this approach for this use case would be very useful to customers that have this scenario.

### Are you able to collaborate and/or submit a pull request?

Yes