Feature: Export to PowerPoint with presenter notes

[QuinnyPig]

Periodically some conferences require that you deliver presentations on their machine, which invariably only has PowerPoint installed. While it's obviously not ideal, reality does sometimes interfere with what we'd otherwise want. Today, there's no straight shot to get that set up.

Proposed Solution
Ideally what marp does or something akin to it would be great: it generates a pptx file as a series of images (just as the current PDF and PNG exports do), and optionally turns the speaker notes into PowerPoint presenter notes.

Potential Alternatives
So far the only solutions I've seen have been manual, or else chaining together eldritch horrors of shell scripts piping to Python utilities. It's the exact opposite of "robust."