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: [[ https://linear.app/comm/issue/ENG-1893/rust-part-code-small-refactors | ENG-1893 ]]