Test binding model with multiple descriptor sets

Test binding model with multiple descriptor sets

Tests were added to verify that multiple descriptor sets can be used
and accessed in all possible shader stages with all possible descriptor
types.

Multiple descriptor sets are updated using
- vkUpdateDescriptorSets
- vkUpdateDescriptorSetWithTemplateKHR

DescriptorSetUpdateBuilder utility class was modified slightly to
work better with multiple descriptor sets.

New tests:

dEQP-VK.binding_model.shader_access.*.*.*.multiple_descriptor_sets.*

Components: Vulkan, Framework

VK-GL-CTS issue: 91

Change-Id: I6c1a719a7a2af74c3f1eb2a620af1ec73c113411