Add formatting function for admire::qos::entity

    }

};

template <>

struct fmt::formatter<std::optional<admire::qos::entity>>

    : formatter<std::string_view> {

    // parse is inherited from formatter<string_view>.

    template <typename FormatContext>

    auto

    format(const std::optional<admire::qos::entity>& e,

           FormatContext& ctx) const {

        if(!e) {

            return formatter<std::string_view>::format("none", ctx);

        }

        std::string_view data = "unknown";

        switch(e->scope()) {

            case admire::qos::scope::dataset:

                data = fmt::format("{}", e->data<admire::dataset>());

                break;

            case admire::qos::scope::node:

                data = fmt::format("{}", e->data<admire::node>());

                break;

            case admire::qos::scope::job:

                data = fmt::format("{}", e->data<admire::job>());

                break;

            case admire::qos::scope::transfer:

                data = fmt::format("{}", e->data<admire::transfer>());

                break;

        }

        const auto str = fmt::format("scope: {}, data: {}", e->scope(), data);

        return formatter<std::string_view>::format(str, ctx);

    }

};

template <>

struct fmt::formatter<admire::qos::limit> : formatter<std::string_view> {

    // parse is inherited from formatter<string_view>.