The builder group is necessary for recipe scripts. A first preliminary
step towards standalone testers.

Note on naming: Chromium bots use "chromium.X". WebRTC and V8 use
"client.webrtc" etc. Going with just "angle" for simplicity.

Bug: angleproject:5114
Change-Id: Ie0e47aa28eaeab4ebe8d13900c1b68cad8a7a1a5
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2805892Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>