[services] Tunnelbroker - Add protobuf file compilation to Cargo build.rs

Summary:
This diff introduces adding the protobuf file compilation to Cargo's build system.
This is an intentional requirement to use Tonic.

Related Linear task: ENG-2094

CI Notes:
CI will fail until the D5461 will be landed.
This diff will re-request CI building before landing it.

Test Plan: Service and Rust-part of the codebase successfully built by running of cargo build command in the services/tunnelbroker directory.

Reviewers: jon, marcin, michal, varun, tomek

Reviewed By: jon, varun, tomek

Subscribers: ashoat, tomek, atul, abosh

Differential Revision: https://phab.comm.dev/D5360