Add support for JXL

[PowerKiKi]

JPEG XL is a brand new image format that is, of course, better than everything else. And especially it made by JPEG committee themselves and has clear migration path. That gives it a good chance to actually replace JPG someday.

Since browser support is still behind a flag, there is no hurry for us to implement this. But when we do we'll have to be careful about Gmagick support (Imagick already supports it)

[PowerKiKi]

Before doing anything, we must check if chrome actually dropped support for it, or if they reintroduced it...

[antermin]

Unfortunately, Chrome indeed dropped it since 110.
But the great news is that Apple has become an adopter, and it will be supported by Safari 17 (supported by default, no need to turn on any flags to enable it) and macOS.

• https://caniuse.com/jpegxl
• https://twitter.com/jensimmons/status/1666058844122894336