A lot of times, it's nice to have both the VkQueue and queue index. I propose we add this convenience function to vkb::Device:

vkb::Result<std::pair<VkQueue, std::uint32_t>> vkb::Device::get_queue_and_index(vkb::QueueType type) const;

Upon failure to fetch the queue index or VkQueue, it would return a result with the respective error. Upon successfully fetching both, it would return a pair of the queue and index.