Add simple lightbox feature to markdown images

Open username-removed-419825 requested to merge 28387-lightbox-for-quick-image-zoom into master

What does this MR do?

  • Open full-screen view of image in a lightbox when clicked

Why was this MR needed?

  • Improve the UX of viewing images in MRs and Issues

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

What are the relevant issue numbers?

Closes #28387 (closed)