Vulkan: Stop passing both ProgramExecutable and ...Vk around Now that ProgramExecutableVk is accessible through ProgramExecutable. Bug: angleproject:8297 Change-Id: Ie08770ef97400195d63b87f2d4b7e2a2c8f4ad24 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4812147 Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Yuxin Hu <yuxinhu@google.com>