This cl adds logic to propagate the 4th texture coordinate,
which is only used for cubemap arrays, and use it as the
cubemap array id.

Tests: dEQP-VK.glsl.texture_functions*cubearray*
Bug: b/144988970
Change-Id: I241b9a50a87424461647f00d442774ead8aaa0f7
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38876
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>