Fix invalid AVIF

The existing file has a number of errors common in older writers:
- [miaf][Rule mdn#4] Error: 'hdlr' not found in MetaBox
- [miaf][Rule mdn#26] Error: Found no 'pixi' associated for 2 displayable (not hidden) images (ItemIds={1,2})
- [heif][Rule #0] Error: 'mif1' brand not found in 'ftyp' box
- And several others

See https://gpac.github.io/ComplianceWarden-wasm/avif.html for details.

This replaces it with a valid AVIF encoded from large-balloons.jpg with
avifenc from https://github.com/AOMediaCodec/libavif.

Author: baumanj