[native/rust_library] Adding CXX bridge names for C++ Identity service client functions

Summary:
This diff introduces adding the C++ names for the exposed Rust functions which will override the Rust function names to meet our C++ function names convention and make their usage in the C++ codebase clear.

Linear task: ENG-1333

Test Plan: Rust library and native app are successfully built.

Reviewers: varun, jon, tomek

Reviewed By: varun, jon, tomek

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D5969