[tunnelbroker] Create thread-safe wrapper over AMQP connection

Summary:
Thread-safe wrapper over lapin connection, along with channel pool.
Now implemented initial connection creation, this functionality is extended in the next diffs

Depends on D13600

Test Plan: Tested together with the rest of the stack. Test plan in D13595

Reviewers: kamil, varun, will

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D13601