printing: Allow additional vendor items in print ticket

Presently only specific attributes are allowed in the vendor items of a
cloud job ticket.  The capabilities of a printer include a list of
vendor items that the printer supports.  This change will allow any of
these vendor items the printer supports, in addition to the explicit
list already present.

Bug: 312940506
Change-Id: I9b39ca5093187f87c56e7772eee08eb3d7b4c5d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5356496


Reviewed-by: Piotr Pawliczek <pawliczek@chromium.org>
Commit-Queue: Nathan Muggli <nmuggli@google.com>
Cr-Commit-Position: refs/heads/main@{#1270538}