Fixes the format table so the correct Vulkan format for the types are
generated.  Additionally, implements CHROMIUM_copy_compressed_texture as
well as other functions relevant to initializing compressed textures.

Bug: angleproject:2670, angleproject:2904
Change-Id: I682d36574262525027cddf8f329515f38cd77dc0
Reviewed-on: https://chromium-review.googlesource.com/c/1468048
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@google.com>