anv: Implement VK_EXT_descriptor_indexing

Now that everything is in place to do bindless for all resource types
except input attachments and UBOs, VK_EXT_descriptor_indexing is
"trivial".

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>

docs/relnotes/19.1.0.html

@@ -46,6 +46,7 @@ TBD.
 <li>GL_KHR_parallel_shader_compile on all drivers.</li>
 <li>VK_EXT_buffer_device_address on Intel and RADV.</li>
 <li>VK_NV_compute_shader_derivatives on Intel.</li>
+<li>VK_EXT_descriptor_indexing on Intel.</li>
 </ul>
 
 <h2>Bug fixes</h2>