This diff introduces changes using the `rust::notifications` namespace for calling Rust notification functions from C++.
At the moment in Tunnelbroker, we are calling the Rust function without using namespaces. The Rust functions are exposed as global to C++. The better way is to use [[ https://cxx.rs/attributes.html?highlight=namespace#namespace | namespaces in Rust ]] code to expose it to C++ codebase.
Related Linear task: [[ https://linear.app/comm/issue/ENG-1894/calling-rust-function-from-c-using-the-namespace-in-tunnelbroker | ENG-1894 ]]