Added implementation for Depth and Stencil which currently allocates
Depth and Stencil as 2 contiguous image planes in memory.

Copying to and from depth and stencil planes is now supported which
fixes all failures in:
dEQP-VK.api.copy_and_blit.core.image_to_image.all_formats.depth_stencil
Which were the last remaining failures in:
dEQP-VK.api.copy_and_blit.core.image_to_image

Bug b/119620767

Change-Id: Ie90737c219c70d9c8a68c024ed33292812a3b7f4
Reviewed-on: https://swiftshader-review.googlesource.com/c/23209Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>