Thumbnail support for .heic attachments

[bronwyncombs]

Requested by Alexis from Le Muséum d’histoire naturelle de Genève via BoldBesk #1092

Info:

.heic is the primary type of High-Efficiency Image File Format (HEIF) used.

HEIF is the international standard defined by MPEG-H Part 12 (ISO/IEC 23008-12), first published by ISO in 2017 (https://www.loc.gov/preservation/digital/formats/fdd/fdd000526.shtml).

[bronwyncombs]

Added to asset server repo: specify/web-asset-server#43