Vulkan: Create TransformSpirvCode() To support Program Pipeline Objects, the SPIR-V transformations must be completed at draw time once all of the variable locations are known. To achieve this, the transformation work is being refactored into TransformSpirvCode() which can be called separately from GlslangGetShaderSpirvCode(). Bug: angleproject:3570 Change-Id: Ia479cb2e4b4201e37acd0859c70081cecb80d0bf Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2068900 Commit-Queue: Tim Van Patten <timvp@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>