Vulkan: Refactor extension vs core version checks Extensions are now grouped based on promotion-to-core status, and initialization code is generally cleaned up. ANGLE currently doesn't attempt to use a core version above Vulkan 1.1, as extensions are always assumed to be exposed even if promoted to core in later versions. With this change, it would be simpler to use a newer core version if ever necessary. Bug: angleproject:7959 Change-Id: Ia5fd3e06c18f7289e9e5a63af0f039a6dc89c687 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4224582 Auto-Submit: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Ian Elliott <ianelliott@google.com> Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>