Test generating mipmaps with vkCmdBlitImage()

Test generating mipmaps with vkCmdBlitImage()

Tests were added to verify that the typical use-case of generating
mipmap levels with vkCmdBlitImage() works for all supported
formats.

Tests in 'from_base_level' group use the base image as a source for all
mip levels and generate all mip levels with a single blit command.

Tests in 'from_previous_level' group use the previous mip level as a
source for the next mip level and generate each mip level with a
separate blit command with barriers between each blit.

New tests:

dEQP-VK.api.copy_and_blit.core.blit_image.all_formats.generate_mipmaps.*
dEQP-VK.api.copy_and_blit.dedicated_allocation.blit_image.all_formats.generate_mipmaps.*

Components: Vulkan

VK-GL-CTS issue: 85

Change-Id: I7a9a432b6ed838e4b97649bfae0e3445b2614256