[services] Tunnelbroker - AMQP tests

Summary:
AMQPManager - is an internal class for use with the RabbitMQ message broker. It performs connect and re-connect, sends and receive messages from the queue.
When the AMQPManager receives the message it pushes it to the DeliveryBroker local queue.

AMQP tests that we perform:

• Send by AMQPManager and Listen -> Receive message by DeliveryBroker.

Test Plan: Run yarn test-tunnelbroker-service all tests are run and succeed.

Reviewers: karol-bisztyga, palys-swm, varun

Reviewed By: karol-bisztyga, palys-swm

Subscribers: ashoat, palys-swm, Adrian, atul, karol-bisztyga, benschac, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3653