Issue 246 auth backend

[JadeKharats]

WHAT is this pull request doing?

Allows ConnectionFactory to use a chain of responsibility to authenticate users via multiple configured providers. A cache management is implemented to avoid calls that are too slow in http

WIP :
Initialize auth_chain with config.
Find a solution so that external auth services return LavinMQ::User

HOW can this pull request be tested?

Added fake auth_http_backend server in helper.
Cache and auth_chain have dedicated tests

[github-actions]

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

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I have read the CLA Document and I hereby sign the CLA

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2 out of 5 committers have signed the CLA.
✅ (JadeKharats)[https://github.com/JadeKharats]
✅ (spuun)[https://github.com/spuun]
❌ @viktorerlingsson
❌ @carlhoerberg
❌ @kickster97
_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.}

[JadeKharats]

I have read the CLA Document and I hereby sign the CLA

[kickster97]

Awesome!
I need access/rights to the fork repository in order to cherry pick code into the Oauth2 branch