Sort the formats in a meaningful way, so that even if the structure of
the source files change, the order can be maintained. This makes it
easier to review further changes that affect the autogenerated texture
format table.

BUG=angleproject:1318
BUG=angleproject:1244
TEST=angle_end2end_tests

Change-Id: Id3602a809137da43431144a31e36d4a0ed2e596e
Reviewed-on: https://chromium-review.googlesource.com/328250Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>