[Pkg-rust-maintainers] Bug#1079302: rust-image: please provide feature avif-encoder

[Jeremy Bícha]

This required more work than only packaging rav1e. I needed to package
dav1d and ravif and mp4parse and several of their dependencies. Once
those make it through NEW and into Unstable, we can look at removing
the relevant lines of
https://salsa.debian.org/rust-team/debcargo-conf/-/blob/master/src/image/debian/patches/relax-deps.diff

Thank you,
Jeremy Bícha