Issue: Option to inser width="" and height="" attributes on images

Height is not specified in the style properties due to the effect CSS-height has on responsiveness. Instead, a fluid padding is used to size the height, because padding is oddly a function of the browser width.

If you have the lazy-loading settings at their default values, you should not have any re-flow / cumulative layout shift. If lazy-loading is turned on, there are actually no images (except loading indicators) on the page at render time. All the loading indicators are in pre-sized containers (divs) based on the expected dimensions of the final images, and all images are inserted into these placeholder containers later by the lazy loader.

For the next release, I have updated the lazy-loader so that after the images are loaded in, the width and height attributes (not style-height) are also set when they get inserted. I don't think this really makes any functional difference, aside from completeness. At first inspection, doing it this way does not appear to negatively affect responsiveness.

I'm pretty sure that PageSpeed will still complain because I doubt it scrolls the page / waits for the lazy loader to make its analysis.