Webp as Jpeg alternative in Blocs

[Blocs_User]

@Flashman

I have no idea how this would be implemented but I would imagine something like an image bric with the ability to choose two images with one designated for Jpeg and the other for AVIF or WebP.

srcset - for both WebP & AVIF
src - for fallback

Seems like it should not be anything major within Blocs for either. Users drop the images respectively in an image well in the side bar for each source type occurrence and fallback. Then Blocs creates/modifies the source with references to each using srcset & src.