Tests for VK_KHR_separate_depth_stencil_layouts

Tests for VK_KHR_separate_depth_stencil_layouts

Test coverage for VK_KHR_separate_depth_stencil_layouts. See
https://gitlab.khronos.org/vulkan/vulkan/merge_requests/3172

This change modifies several test groups to use a single
image aspect bit for depth+stencil formats rather than the
VU required D+S aspects.

Where appropriate the tests are also modified to use
the new depth-only or stencil-only optimal layouts.

Affects:

dEQP-VK.api.copy_and_blit.*d16_unorm_s8_uint*
dEQP-VK.api.copy_and_blit.*d24_unorm_s8_uint*
dEQP-VK.api.copy_and_blit.*d32_sfloat_s8_uint*

dEQP-VK.api.image_clearing*d16_unorm_s8_uint*
dEQP-VK.api.image_clearing*d24_unorm_s8_uint*
dEQP-VK.api.image_clearing*d32_sfloat_s8_uint*

dEQP-VK.pipeline.stencil*d16_unorm_s8_uint*
dEQP-VK.pipeline.stencil*d24_unorm_s8_uint*
dEQP-VK.pipeline.stencil*d32_sfloat_s8_uint*

dEQP-VK.pipeline.depth*d16_unorm_s8_uint*
dEQP-VK.pipeline.depth*d24_unorm_s8_uint*
dEQP-VK.pipeline.depth*d32_sfloat_s8_uint*

dEQP-VK.*.depth_stencil_resolve*d16_unorm_s8_uint*
dEQP-VK.*.depth_stencil_resolve*d24_unorm_s8_uint*
dEQP-VK.*.depth_stencil_resolve*d32_sfloat_s8_uint*

Change-Id: I147f3736614cc897f1319c5aac5ed1fdba2d7b66
Compontents: Vulkan