This allows us to run angle_end2end_tests with a single config without
using gtest_filter. It will also allow us to run each test config in
a separate process.

Bug: angleproject:3393
Change-Id: I09aaf9cfe55a117b0af8d79ecfd129f3d0f1d7c8
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1591427
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>