The keys in vk_format_map.json were incorrect.  The format table
generation script is enhanced to give an error in such a case.  This
revealed a number of entries with no corresponding angle format, which
are also removed.

Bug: angleproject:2898
Bug: angleproject:3190
Change-Id: I32caf2d2a8abb6f76b25436725670a8e84d576fb
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1666700
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>