Management UI: extend Get Message feature to streams

[LoisSotoLopez]

Proposed Changes

Extends the management endpoint for retrieving messages from a queue allowing this operation to be applied to stream queues. Alters the queue.ejs template to show the Get messages box when showing a stream queue information.

Types of Changes

What types of changes does your code introduce to this project? Put an x in the boxes that apply

• [ ] Bug fix (non-breaking change which fixes issue #NNNN)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause an observable behavior change in existing systems)
• [ ] Documentation improvements (corrections, new content, etc)
• [ ] Cosmetic change (whitespace, formatting, etc)
• [ ] Build system and/or CI

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask on the mailing list. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• [x] I have read the CONTRIBUTING.md document
• [x] I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] All tests pass locally with my changes
• [ ] If relevant, I have added necessary documentation to https://github.com/rabbitmq/rabbitmq-website
• [ ] If relevant, I have added this change to the first version(s) in release-notes that I expect to introduce it

Further Comments

[michaelklishin]

Before you spend any more time on this feature, have you considered consulting with the core team as to whether this feature has any chance of being accepted? Or, perhaps, whether it should use the Erlang AMQP 0-9-1 client? Or any client at all and not an internal API?

I'd very much like to see contributors, even those who contribute mere 1-2% of R&D despite directly making money off of RabbitMQ, to spend their time on more fundamental issues like https://github.com/rabbitmq/rabbitmq-server/issues/11038 or https://github.com/rabbitmq/rabbitmq-server/pull/10763 (two examples of much more fundamental problems it does not take that deep an understanding of RabbitMQ internals to work on).

Specifically around streams, https://github.com/rabbitmq/rabbitmq-website/pull/1885 is infinitely more important for stream adoption than this feature.