struct radix_sort_vk_buffer_info

This structure has semantics similar to VkDescriptorBufferInfo except that

it's missing the `.range` member and includes a buffer device address value.

As noted above, this structure serves two purposes:

* Bridge missing functionality in Vulkan. Namely, a number of older

commands do not yet have pure device address equivalents while recently

added commands (e.g. "acceleration" commands) do not depend on VkBuffer

arguments.

* Integrate with libraries that might be *below* the public Vulkan API. In

this case, the .buffer and .offset values would likely be ignored and

driver-internal FILL and DISPATCH functions would accept device

addresses.