Export book as slides

[acbart]

The MVP of this is the ability to export a version of the book as powerpoint slides that mimic Greg's original version. This should include theme at least, with the content all readable in terms of layout.

Eventually, I'd like to have support for:

• Smart layout, to fit content more nicely on one page when needed
• Basic animations/multiple pages, to let us control when certain things appear
• Material that is in the book view, but not on the slides, and vice versa. This is particularly for longer code examples, that we can redact in the slides (since they don't have to be fully runnable). Might also be for quiz questions or something, or "extra information".

I'll need to do some digging into custom directives, and what makes the most sense. But we should be able to leverage a lot from the Bake Mark project!

[acbart]

So I have a very rough draft of this pipeline. It does actually produce powerpoint files: https://boots-edu.github.io/textbook/assets/slides/0-introduction-welcome.pptx

However, there's a lot wrong with the output, in terms of text layout, headers, and title slides. But the biggest issue is that, I believe, the syntax highlighted images being generated are corrupting the file somehow. I inspected the image files generated between my computer and the github actions, and it seems like there's something subtly different. Need to investigate a lot more.

But it does work, and it's integrated into our deploy pipeline!

[acbart]

That said, I'm not convinced this is the way to go. I'm going to investigate Marp and other related tools to see if they produce a cleaner result. I don't want to rewrite the wheel.

[acbart]

The latest version is looking much better. They're not quite perfect, some slides do run over, but most of them don't suffer from this.