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>