Vulkan: Add driver uniforms set. This will be used to specify the applied Vulkan. We will use this to implement OpenGL line rasterization rules. Bug: angleproject:2717 Change-Id: I3395bf620a01c4b84b19a00037d05f148e5523f3 Reviewed-on: https://chromium-review.googlesource.com/1120151 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Luc Ferron <lucferron@chromium.org>