[Event Hubs] Make mock-hub public

[HarshaNalluru]

From a discussion with @richardpark-msft..

It would be beneficial to our stress tests if we expanded mock-hub to be a fault-injector and be made publicly available for the other languages as well

• to understand how our AMQP SDKs handle the faults and improve
• reproduce unintended/hard-to-debug user issues
• other languages can leverage for their stress testing scenarios
• As a stretch goal, we can blog about it and guide our customers on experimenting with different kinds of loads

@richardpark-msft please add more details on the customizations you would like to see or any specifics in the work involved for this

[richardpark-msft]

Some things that'd be cool:

• Providing a way to slow down any particular interaction - for instance, taking a long time to respond to a DISPOSITION/FLOW/DETACH frame, or even just outright timing out.
• Configurable DETACHes from the service side.
• Configurable connection drops. Providing a way to make these deterministic will make writing certain stress tests more reliable and easier to troubleshoot.

I was thinking some of these behaviors might be triggerable by just including some extra metadata in the ATTACH properties, or (in some cases) in the frame itself, depending. I'd need to dig through some more to give you more but I think the big wins are going to be in connection drops, and slow responses.

Parallelism is also interesting, but I don't think we need to "perf test" against this broker - it's there more to provide nice controllable failures.

[richardpark-msft]

Other options would be to let me configure things via an AMQP endpoint, so we wouldn't need to muck with our normal AMQP messages.

For a "first pass" I think it'd be perfectly fine if you just did this stuff randomly, just to see how we do.

[richardpark-msft]

Just for reference he's what we have for HTTP today:
https://github.com/Azure/azure-sdk-tools/blob/main/tools/http-fault-injector/README.md