AV1 Codec support

[alxmrs]

AV1 is a more performant codec and royalty free.

https://blog.mozilla.org/en/mozilla/royalty-free-web-video-codecs/

Thanks so much for writing this library. I’ve been thinking about the same idea myself for a bit (zarr-developers/zarr-specs#157) and I’m glad a team out there is building it!