Vulkan Validation Layers (VVL) automatically rejects and
removes any unknown pNext pointer in an pNext chain
submitted to the driver. For this purpose, a mechanism was
introduced by VVL in order to allow ANGLE to allow some of
our custom pNext entries to go through VVL without being
removed. This had been used for only 1 of the 3 entries in
the VK_EXT_provoking_vertex extension, causing it to be
properly exposed, but impossible to use. This CL corrects
this by adding the missing entries.

Bug: angleproject:5902
Change-Id: If6478b3aa776513b92420736fa1216b014320b02
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2854815Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Alexis Hétu <sugoi@chromium.org>