Vulkan: Add specialization constants for surface rotation This plumbing through the specialization constant for surface rotation from ContextVk to pipeline program creation. It has not been used yet, so expecting no real functional change. This CL also converts lineRasterEmulation to use the same specialization constant path as surface rotation. Bug: b/171750979 Change-Id: Ic08c4f8bb576424d1752015e874d0977a58d78bb Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2508837 Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Reviewed-by: Ian Elliott <ianelliott@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>