Added Application Registration to AzureAD for RabbitMQ testing purpose

[kratkyzobak]

Added AzureAD Application Registration to enable test of Azure Workload Identity auth against RabbitMQ as proposed in kedacore/keda#4657

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Related to kedacore/keda#4657

[JorTurFer]

I guess that we will need to add more applications in the future. Could you create the module more abstract in order to reuse it?
I think that we can achieve it just moving this code to outside the module and passing it as variable:

application_name             = "${var.unique_project_name}-rabbitmq-app"
rabbitmq_roles = {
  management = "tag:management"
  administrator = "tag:administrator"
  read_all = "read:*/*/*"
  write_all = "write:*/*/*"
  configure_all = "configure:*/*/*"
}

(and renaming the resources, ofc)

[kratkyzobak]

@JorTurFer refactored to make it more generic module for app registraion.

[JorTurFer]

LGTM!

[JorTurFer]

There is an issue with the SP permission in our side, I'll update the issue once it's solved

[JorTurFer]

Done, the app has been created! 😄