Method is_end

Source/external/json.hpp:12686–12689

return whether the iterator is at end

	/// return whether the iterator is at end
	constexpr bool is_end() const noexcept
	{
		return m_it == end_value;
	}

	friend constexpr bool operator==(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
	{