createOptimizedPicture should set img width/height attributes

[stefanseifert]

Expected Behaviour

the img element generated by createOptimizedPicture should contain width/height attributes.

Actual Behaviour

the current implementation of createOptimizedPicture generates images without specifying width/height attributes - google pagespeed complains about this, and it often leads to cumulative layout shift (CLS).

please note that the actual width/height of the source image is not part the URL that is used as src input parameter, and is not contained in the data generated by query-index.