Translators: Add an AVIF translator

This translator only supports still images for now, and supports both
decoding and encoding.

Encoding support has been tested only with aom, rav1e doesn’t build on
Haiku yet, see https://github.com/haikuports/haikuports/pull/5534 for
one of the missing dependencies.

Change-Id: I716f4b862ed316b89b227bfed38072d72074201f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3040
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>