Make Gfx Enum types use 8 bits where possible

No performance improvement was measured with this change. This may
allow better packing in structs.

Possible bugs this could introduce:
Padding bugs when mem-hashing (the padding is not initialized)
Integer math operations on int which are now on uint8_t

Change-Id: Iec1a4304137e28adb611ce6de2b5889ad97d75e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4295658


Commit-Queue: Peter McNeeley <petermcneeley@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: ccameron chromium <ccameron@chromium.org>
Reviewed-by: Miguel Casas-Sanchez <mcasas@chromium.org>
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1111655}