Vulkan: Fix off-by-1 180/270-rotated CopyTexImage The rotation calculations are a little different for this code (that uses a special shader) than for other pre-rotation cases. I also modified the CopyTexImageTestES3.2DArraySubImage test to make future bugs a little easier to diagnose. Test: Test: angle_end2end_tests --gtest_filter=*CopyTexImageTestES3.2DArraySubImage*Vulkan* Test: Test: angle_end2end_tests --gtest_filter=*WebGLReadOutsideFramebufferTest.CopyTexSubImage2D*Vulkan* Bug: b/158245571 Change-Id: I497ec541cae5cd4085c3e9d596ee20943f5510f9 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2275733 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Ian Elliott <ianelliott@google.com>