Vulkan: Implement sampler arrays. Bug: angleproject:2462 Change-Id: If9c9cb69624d6f9f0895f6883e1eed19a27e6cb4 Reviewed-on: https://chromium-review.googlesource.com/1089809 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Frank Henigman <fjhenigman@chromium.org>