Vulkan: Add uniform descriptor set caching test. This covers the case where we'd continually miss the cache due to buffer size mismatches. Bug: angleproject:6980 Change-Id: Ia58871f431b6241af52fa0c37ab51952bc1c4f97 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3469227 Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org> Auto-Submit: Jamie Madill <jmadill@chromium.org>