Feature: Allow shareable links for anything with a source image (right now, only text2text links are shareable and have embeddable media)

[daveschumaker]

Context on Discord via EFreak:

I just want to share the preview/prompt, I don't care about the source image, you can get pretty similar without it, or I can just share the source image

Might be worth using the URL function for source images? Since I frequently pull images from websites anyways, it would work. Or you could just pop a warning on loading it that it's based on a missing source. I wanted to share a generated image/prompt with the place I got the original from, they already have the source