JPEG XL support

[flozz]

See @nekohayo issue on YOGA Image Optimizer → https://github.com/flozz/yoga-image-optimizer/issues/20

[nekohayo]

Here's an example primitive implementation of a batch JPEG XL encoding script in Python: https://github.com/kylxbn/jxl-migrate

It simply calls the cjxl binary with the desired file, and passes -d 0 (mathematically lossless, gives you roughly 15-20% filesize saving when converting existing JPEGs) or -d 1 (visually indistinguishable lossy transcoding, gives you roughly 50 to 90% filesize reduction from a regular JPEG source, according to this man page). cjxl doesn't seem to have a parameter for resizing though, I don't know if that's a problem.

In case this is somehow helpful...

[flozz]

YOGA never call external binaries, it always use libraries directly. It avoid having to write temporary files and it is more reliable to target multiple systems (various Linux distro, Windows,...) :)