This extension allows users to pass depthstencil attachments that
vkCmdResolveImage will resolve to in addition to its other resolve
operations. Only the mandatory resolve modes
"VK_RESOLVE_MODE_SAMPLE_ZERO_BIT" and "VK_RESOLVE_MODE_NONE" are
supported.

It's trivial to support both independent resolve modes since we must
resolve depth and stencil attachments separately due to how depth and
stencil attachments are stored internally.

Change-Id: I0f8ff7cddca5f5acbac1d991b11f0a4447956784
Bug: b/167558951
Test: dEQP-VK.renderpass2.depth_stencil_resolve.*
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/48808Tested-by: Sean Risser <srisser@google.com>
Commit-Queue: Sean Risser <srisser@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>