[Tunnelbroker] Add amqp client crate, add minimal usage

Summary:
lapin seems to be the most commonly used. It is:

• Still actively maintained
• MIT licensed
• Supports much of amqp v0.9.x

Part of https://linear.app/comm/issue/ENG-3716

Test Plan: N/A

Reviewers: ashoat, varun, bartek

Reviewed By: bartek

Subscribers: atul, tomek

Differential Revision: https://phab.comm.dev/D8177