vk: Build binding tables at bind descriptor time

vk: Build binding tables at bind descriptor time

This changes the way descriptor sets and layouts work so that we fill
out binding table contents at the time we bind descriptor sets. We
manipulate the binding table contents and sampler state in a shadow-copy
in anv_cmd_buffer. At draw time, we allocate the actual binding table
and sampler state and flush the anv_cmd_buffer copies.