Vulkan: Add "ImageViewHelper". This allows views to track a different lifetime than vk::ImageHelper. This in turn will fix the race condition on ContextVk destruction when releasing ImageViews owned by TextureVk and RenderbufferVk. For now this is a refactoring change only. Bug: angleproject:2464 Change-Id: I9581975bd5d4913233bbed8439dd4a632cc78a2a Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1843231 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Ian Elliott <ianelliott@google.com>