markdown preview: Allow clicking on image to navigate to source location (#21630)

Follow up to #21082

Similar to checkboxes, you can now click on the image to navigate to the
source location, cmd-clicking opens the url in the browser.


https://github.com/user-attachments/assets/edaaa580-9d8f-490b-a4b3-d6ffb21f197c


Release Notes:

- N/A