add utility function for converting an exception to a Status

Status myFunc() {

    try {

        funcThatThrows();

        return Status::OK();

    } catch (...) {

       return ExceptionToStatus();

    }

}

Status ExceptionToStatus() {

    try {

        throw;

    } catch (const DBException& ex) {

       return Status(...)

    } catch (const std::exception& ex) {

        .....

    }

    .....

}