Add VkPhysicalDevicePortabilitySubsetFeaturesKHR:: samplingImplicitLODProjectedGeometryAccuracyConformance capability

Some CTS tests fail on the sampling accuracy of all pixels when using mipmap sampling on projected geometry.

This might be fixable with generally relaxed testing thresholds on the CTS tests.

In the meantime, these use cases can be disabled in CTS and reported as Not Supported, by adding a VkPhysicalDevicePortabilitySubsetFeaturesKHR:: samplingImplicitLODProjectedGeometryAccuracyConformance capability.

This affects 30 CTS tests:

dEQP-VK.texture.mipmap.2d.projected.nearest_nearest_clamp
dEQP-VK.texture.mipmap.2d.projected.nearest_nearest_repeat
dEQP-VK.texture.mipmap.2d.projected.nearest_nearest_mirror
dEQP-VK.texture.mipmap.2d.projected.linear_nearest_clamp
dEQP-VK.texture.mipmap.2d.projected.linear_nearest_repeat
dEQP-VK.texture.mipmap.2d.projected.linear_nearest_mirror
dEQP-VK.texture.mipmap.2d.projected.nearest_linear_clamp
dEQP-VK.texture.mipmap.2d.projected.nearest_linear_repeat
dEQP-VK.texture.mipmap.2d.projected.nearest_linear_mirror
dEQP-VK.texture.mipmap.2d.projected.linear_linear_clamp
dEQP-VK.texture.mipmap.2d.projected.linear_linear_repeat
dEQP-VK.texture.mipmap.2d.projected.linear_linear_mirror

dEQP-VK.texture.mipmap.cubemap.projected.nearest_linear_nearest_clamp
dEQP-VK.texture.mipmap.cubemap.projected.nearest_linear_nearest_repeat
dEQP-VK.texture.mipmap.cubemap.projected.nearest_linear_nearest_mirror
dEQP-VK.texture.mipmap.cubemap.projected.nearest_linear_linear_clamp
dEQP-VK.texture.mipmap.cubemap.projected.nearest_linear_linear_repeat
dEQP-VK.texture.mipmap.cubemap.projected.nearest_linear_linear_mirror
dEQP-VK.texture.mipmap.cubemap.projected.linear_linear_nearest_clamp
dEQP-VK.texture.mipmap.cubemap.projected.linear_linear_nearest_repeat
dEQP-VK.texture.mipmap.cubemap.projected.linear_linear_nearest_mirror
dEQP-VK.texture.mipmap.cubemap.projected.linear_linear_linear_clamp
dEQP-VK.texture.mipmap.cubemap.projected.linear_linear_linear_repeat
dEQP-VK.texture.mipmap.cubemap.projected.linear_linear_linear_mirror

dEQP-VK.texture.mipmap.3d.projected.nearest_linear_clamp
dEQP-VK.texture.mipmap.3d.projected.nearest_linear_repeat
dEQP-VK.texture.mipmap.3d.projected.nearest_linear_mirror
dEQP-VK.texture.mipmap.3d.projected.linear_linear_clamp
dEQP-VK.texture.mipmap.3d.projected.linear_linear_repeat
dEQP-VK.texture.mipmap.3d.projected.linear_linear_mirror
  Fail (fail)

Start by locating the listed dEQP-VK.texture.mipmap projected-geometry CTS tests and the Vulkan Portability Subset feature definitions. Check how portability capabilities cause tests to report Not Supported, then verify that the affected projected 2D, cubemap, and 3D tests are handled consistently.