This changes the TextureVk class to have a queue of staging
copies, instead of a single copy at a time. This will allow
us to upload multiple sub regions of a texture image at once
when we need to resolve the Image at sampling time.

Enables the remainder of the texture.format tests, and all
non-mipped tests in the texture.size tests. Also updates the
expectations with the bug number for mipmap support.

Bug: angleproject:2318
Change-Id: Ie55f8f2dc24d7b133ad735e37f0f78937f022b5b
Reviewed-on: https://chromium-review.googlesource.com/980775Reviewed-by: Luc Ferron <lucferron@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>