Vulkan: Move SPIR-V transform to vulkan/
No longer used by metal/.
Bug: angleproject:7220
Change-Id: Idb3a6369fefbcf87e7993daa652c8702ec53c20f
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4104002
Reviewed-by: Yuxin Hu <yuxinhu@google.com>
Auto-Submit: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Yuxin Hu <yuxinhu@google.com>
