Add AtomicCounterIncrement test case.

BUG=angleproject:3246

Change-Id: I6e74f349b758c3ae9fcb44a14e70d36495406dfd
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1768017
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>