[services] Tunnelbroker - Expose isSandbox to the Rust
Summary:
In this diff, we are exposing a function to get if the server is running a sandbox mode from the C++ codebase to the Rust codebase as a isSandbox function.
This function will be used in the Rust codebase diff D5641 and forward.
Linear task: ENG-1893
Test Plan:
- Service is successfully built.
- The diff D5641 where the function is used the service is successfully built.
Reviewers: jon, varun, marcin
Reviewed By: jon
Subscribers: ashoat, tomek, atul, abosh
Differential Revision: https://phab.comm.dev/D5640