The implementation is based heavily on the Chromium Skia Gold
Python classes in //build/skia_gold_common .

Results will be visible here: https://angle-gold.skia.org/
Currently results are not visible until this CL lands.

Bug: angleproject:4090
Bug: b/168049670
Change-Id: I7a5d64fe35583ad7ea6360804a0f6b72cd9f6d8b
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2430179Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>