- Correctly claim that VK_FORMAT_S8_UINT has quadlayout. This is the
  only layout the ROP code understands for stencil. This by itself will
  cause blitter ops to take it into account.

- Clean up the unused but misleading 'useStencil' flag in
  Blitter::Options

- Mark the cases we don't yet support in Image<->Image and Image<->Buffer
  copies as UNIMPLEMENTED. These will be corrected in followup patches.

Bug: b/132156862
Test: dEQP-VK.api.*
Test: dEQP-VK.image.*
Test: dEQP-VK.renderpass.*
Change-Id: I26ccc82a17fb44043ea9624988473e3835069c71
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/30770Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>