Vulkan: Add test for RGB texture not break renderpass This adds a test that will use an empty RGB texture. It should not break renderpass. Bug: b/162603208 Change-Id: I90f5aa2fafdbd70c654c9ad0675d6def32b58313 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2338828 Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com>