anv: Implement VK_KHX_external_memory_capabilities

anv: Implement VK_KHX_external_memory_capabilities

This is a complete but trivial implementation. It's trivial becasue We
support no external memory capabilities yet.  Most of the real work in
this commit is in reworking the UUIDs advertised by the driver.

v2 (chadv):
  - Fix chain traversal in vkGetPhysicalDeviceImageFormatProperties2KHR.
    Extract VkPhysicalDeviceExternalImageFormatInfoKHX from the chain of
    input structs, not the chain of output structs.
  - In vkGetPhysicalDeviceImageFormatProperties2KHR, iterate over the
    input chain and the output chain separately. Reduces diff in future
    dma_buf patches.

Co-authored-with: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Chad Versace <chadversary@chromium.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>