- OpLoad of pointer to descriptor is passthrough; reflect that in Kind.
- Actually pass through all the descriptor types in EmitLoad
- Fix Walk*AccessChain to not create useless divergence; constant offset
  was added in the wrong place.
- Adjust WalkAccessChain to adjust pointers into descriptor arrays using
  the descriptor stride
- Adjust storage image descriptor content to not assume layerPitch ==
slicePitch, since that isn't true.

Bug: b/131082089
Test: dEQP-VK.binding_model.*
Test: dEQP-VK.spirv_assembly.*
Test: dEQP-VK.glsl.*
Change-Id: I6cc4ae7b0fdeb54ede111f532c7e3fd1f108803c
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/29549Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>