Implement the unoptimized-lossless-images feature policy.

This is similar to the existing unoptimized-lossy-images policy, but
instead enforcing images with lossless (or no) compression algorithms
(BMP, GIF, PNG, WEBP).

This is a follow-up to
https://chromium-review.googlesource.com/c/chromium/src/+/1531354

Bug: 942659
Change-Id: Ic6a4d2188b820383d8b077efd52a7bf6896ff8bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1540259
Reviewed-by: Ian Clelland <iclelland@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Paul Meyer <paulmeyer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#645787}