Base64 encoded images embedded in SVGs are not supported in DOCX or MS Word

As of now, when including either raster or vector images into a document, and exporting to SVG format, typst always encodes the embedded images to base64.

While that's necessary for rasters, vectors could be embedded raw, without base64 encoding, and therefore would be loadable by Microsoft Word.

There was a recent PR implementing raw SVG embedding that was halted due to security concerns: #6814

And the related issue: #6812

I would propose to maybe put raw embedding behind a compiler flag, as to keep the more secure behavior as default, while still allowing Typst to produce fully MS Word-compatible SVGs.

Source about b64 embeds incompatibility with MS Word: https://learn.microsoft.com/en-us/answers/questions/1324557/is-word-document-read-base64-image-format?hl=it-IT

Start by reviewing the halted raw SVG embedding PR #6814 and related issue #6812, then trace the SVG export behavior described here. Done means producing SVGs that Microsoft Word can load while retaining the secure default behavior, with any opt-in compiler flag defined clearly.