Feature Request - Support WebP images and Switch to lazysizes over vue-lazyload

[tonyisworking]

What is the motivation for adding / enhancing this feature?

WebP Image formats are supported by multiple browsers now, supporting it should be good for improved performance.

Switching to lazysizes instead of vue-lazyload will be needed for WebP image formats as Lazysizes supports picture element, where vue-lazyload does not. Picture element can be used to fallback to regular jpegs. Other responsive image techniques can be applied as well.

Sharp supports webp, so updating the images.js output should be straightforward too...

[tonyisworking]

Also there's an example for supporting the modern srcset pattern which should solve issue vuestorefront/vue-storefront-1#307