This moves the Vulkan format table to dynamically generated, but
keeps it easily indexed. Because Vulkan format support is not able
to be fully determined until runtime, we'll need a dynamic way to
build the table. The most straight-forward way seems to be to keep
a copy of the full table in the Renderer. Initializing it once at
startup makes it a bit slower to init, but saves us from any threading
shenanigans with lazy init when (and if) we ever support multi-
threaded Contexts.

BUG=angleproject:2207

Change-Id: Ib1ac879daa562c7ad1a965390be401fa2314e42c
Reviewed-on: https://chromium-review.googlesource.com/742374
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>