This class wraps a lot of the common functionality of a vk::Image.
It keeps an associated DeviceMemory and ImageView.

Eventually we can probably merge this class with  RenderTargetVk. We
can also use it to implement the same functionality between
Renderbuffer and Texture and abstract different storage types, like
2D and Cube.

Bug: angleproject:2318

Change-Id: I39239f47b483cfb96290a15b06edd264f7f4bb34
Reviewed-on: https://chromium-review.googlesource.com/980772Reviewed-by: Frank Henigman <fjhenigman@chromium.org>
Reviewed-by: Luc Ferron <lucferron@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>