Function SzConfigTool_setValidationFunction 

#[unsafe(no_mangle)]
pub extern "C" fn SzConfigTool_setValidationFunction(
    config_json: *const c_char,
    attr_code: *const c_char,
    validation_func: *const c_char,
) -> SzConfigTool_result

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