video/hvif: Add HVIF decoder element

This vector format originates from Haiku, where it is used for icons
thanks to its very small file size, in comparison to SVG or PNG.

This plugin is based on the hvif crate, which uses cairo to do the
rendering, see https://linkmauve.fr/dev/hvif/
12 jobs for !591 with hvifdec in 22 minutes and 19 seconds (queued for 7 seconds)
latest merge request