easy-init: support messaging systems (service bus)

[weikanglim]

Background: @saragluna had started implementation on some Java enhancements in #4422. We will split this into smaller changes to land incrementally.

Work: Add Messaging support. We can limit work for service bus queues for now, but we should think about the design for general pub/sub messaging systems.

One design invariant we have with the current initialization system is that it's largely Azure-agnostic and technology-focused. We could decide to keep this invariant or to design differently if need be.

[saragluna]

Quote:

I think we can avoid "AzureDeps" in appdetect by making this technology focused -- maybe something like MessagingDeps or PubsubDeps, and maybe a break down between Queues and Topics. I'll leave it up to you to do the initial research here on what makes most sense from a messaging technology, language agnostic standpoint.