Function is_number

include/behaviortree_cpp/contrib/json.hpp:20631–20634

@brief return whether value is a number @sa https://json.nlohmann.me/api/basic_json/is_number/

    /// @brief return whether value is a number
    /// @sa https://json.nlohmann.me/api/basic_json/is_number/
    constexpr bool is_number() const noexcept
    {
        return is_number_integer() || is_number_float();
    }

    /// @brief return whether value is an integer number
    /// @sa https://json.nlohmann.me/api/basic_json/is_number_integer/