View images in a lightbox rather than new tab

Context

This issue is the first step towards a vision of viewing image within GitLab:

1. This issue
2. View images in a markdown table with pagination #377399
3. View gallery of images in markdown table #255621 (closed)
4. View gallery in design management #255621 (closed)

Steps for Closure

• Come to agreement on groupknowledge ownership
• Create and agree on final designs
• Carve out and develop 👍

Problem

When viewing an image in GitLab, the image opens in a new tab. I lose the context of where I was.

Proposal

When clicking on images within GitLab, (for example in comments, MRs, issue body...) open the image in a light box style:

#377398[Lightbox.png]

This reuses elements of design management