The Vulkan back-end will be using this helper struct, so make it
available everywhere. This cleans up a lot of the code for D3D.

Potentially in the future we could generate these in the entry
points if we supported packing multiple arguments into one.

Also changes a few parameter types to GLint for compatibility.

Also updates the Vulkan Texture implementation check the stored
vk::Format on setImage changes.

Bug: angleproject:2318
Change-Id: I57cea4a42483ab51859229517d783b58f206b8e7
Reviewed-on: https://chromium-review.googlesource.com/985203
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Luc Ferron <lucferron@chromium.org>