Added option to diff SVG files as images

What does this MR do and why?

This adds 2 buttons to the diff header to allow for users to diff SVG files like images, and allowing full commenting like images, or to diff the SVG as text.

#15284

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screen_Recording_2024-02-16_at_12.53.39

How to set up and validate locally

• Enable the diff_svg_files feature flag
• Create a merge request with an SVG file