Vulkan: Index mandatory support table by ANGLE format. This removes another instance of indexing a flat array by VkFormat. With the introduction of YUV formats we no longer have a compact table. Switching to ANGLE format indexing allows us to keep a flat array and avoid using an unordered map. Bug: angleproject:5438 Change-Id: I96caa19e3b7ce419ce09680399919447f002b0bd Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2622238 Reviewed-by: Ian Elliott <ianelliott@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>