Promoted to core in Vulkan 1.1

This extension is designed around how some applications create and update many VkDescriptorSets during the initialization phase. It’s not unlikely that a lot of updates end up having the same VkDescriptorLayout and the same bindings are being updated so therefore descriptor update templates are designed to only pass the update information once.

The descriptors themselves are not specified in the VkDescriptorUpdateTemplate, rather, offsets into an application provided a pointer to host memory are specified, which are combined with a pointer passed to vkUpdateDescriptorSetWithTemplate or vkCmdPushDescriptorSetWithTemplateKHR. This allows large batches of updates to be executed without having to convert application data structures into a strictly-defined Vulkan data structure.