This is a reland of 38780ae3 modulo the
changes to disable VK_VALIDATION_FEATURE_DISABLE_UNIQUE_HANDLES_EXT, as
this was causing problems. With this landed, the extension will not work
on SwiftShader until we find a way to allow this extension through the
validation layers.

Bug: b/146423360
Bug: b/154620295
Change-Id: Ie09fc507c01a47be3bb227bc78771660170ba5d3
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2199639
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>