Add support for AVIF format

[jonnitto]

Currently, these files formats are supported:
jpg, jpeg, gif, png, wbmp, xbm, webp and bmp

But there is already the next generation of image formats here: AVIF. You can read more about it here

With this option, we could even serve faster websites with Neos 🚀

[bwaidelich]

I removed this feature from the Neos 6.0 project board for now since this requires an update of imagine

[putzwasser]

What's the status of this?

I think imagine got updated:

php-imagine/Imagine#759