Method validate

Bcore/src/main/cpp/Dobby/tests/catch.hpp:6160–6172

  }

  auto validate() const -> Result override {
    for (auto const &opt : m_options) {
      auto result = opt.validate();
      if (!result)
        return result;
    }
    for (auto const &arg : m_args) {
      auto result = arg.validate();
      if (!result)
        return result;
    }
    return Result::ok();
  }

  using ParserBase::parse;