Begin the process of moving our MDX files into their own content directory.
Fixed a few minor bugs re: ToC and tabs not rerendering consistently on page navigation. (The ToC thing wasn't a problem before the refactor, the tabs thing is a problem on prod.)
Moved MDX files can't import their own components, so everything they require needs to be back in the component prop for mdx-remote's serializer. Cleaned this up a bit and lazy-loaded heavy/rare stuff. Also, the component prop doesn't take arbitrary objects (only actual components), so imported data has to be wrapped in a component.
