Vulkan: SPIR-V Gen: texture and image built-ins GLSL contains a large number of built-in texture* and image* functions, but these map to only a handful of SPIR-V instructions. The bulk of the work to map these is to extract the arguments from the built-ins based on their ordinal position. Bug: angleproject:4889 Change-Id: I760d986bd9171ddde35f9f046c549ca53252df17 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2992980 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>