Enable nullDescriptor for AS ray query tests

Enable nullDescriptor for AS ray query tests

Ray query null acceleration structure tests depend on the nullDescriptor
feature, which is not enabled in the default device. The tests need
custom devices, which implies minor design changes all over the ray
query builtin and advanced tests, due to these tests passing the global
context around and obtaining the test device from it in several
different places.

Affected tests:
dEQP-VK.ray_query.builtin.*
dEQP-VK.ray_query.advanced.*

Components: Vulkan
VK-GL-CTS issue: 2635

Change-Id: Ia5215c625b06c590d9b293e5c4d55b53c98a3e7d