Add tests to show bad waitSync/flush behavior Add the following tests to show ANGLE's poor behavior with glWaitSync/glFlush leading to a vkQueueSubmit each time: FenceSyncTest::MultipleFenceDraw MultithreadingTestES3::MultithreadFenceDraw MultithreadingTestES3::MultithreadFenceTexImage Bug: angleproject:5306 Test: FenceSyncTest::MultipleFenceDraw Test: MultithreadingTestES3::MultithreadFenceDraw Test: MultithreadingTestES3, MultithreadFenceTexImage Change-Id: I16f653af028677e3c621c3b9a7fd5963fa03d656 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2519092 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Tim Van Patten <timvp@google.com>