Permuatations of configs are now generated in platform-independent code and
a DisplayVk callback is used to determine native support.

BUG=angleproject:2692

Change-Id: Iad450c1a3275239d6bcbc350e8dd8e37470fa8e0
Reviewed-on: https://chromium-review.googlesource.com/1117563Reviewed-by: Luc Ferron <lucferron@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>