Add a version of GetSrcSetUrls() for background-image image-set()

[filefontaine]

Hello for my website i use a hero background-image and it can be call if you can create a version for this using image-set().

https://developer.mozilla.org/en-US/docs/Web/CSS/image-set Url need to be in "" and resolution need to be in x , dppx , dpi but not w.