Function SzConfigTool_setCandidateFunction 

#[unsafe(no_mangle)]
pub extern "C" fn SzConfigTool_setCandidateFunction(
    config_json: *const c_char,
    rtype_code: *const c_char,
    candidate_func: *const c_char,
) -> SzConfigTool_result

Set (update) a candidate function (placeholder - not implemented)