Find a way to dynamically load heavy dependencies

This library uses katex, which is a big dependency that gets bundled even if you end up not using any of the code branches that use it.

Rollup supports splitting individual code bundle chunks for code that's imported dynamically via `import(...)`, so we could do that with heavy dependencies.

This requires checking how consuming libraries can then also load those chunks on demand, since they will need to be served independently of the main bundle.