Converting Custom Server-Side-Rendered to use FABs

TODO: convert BBC's Simorgh and use it as an example.

While FABs have proof-of-concept conversions for a few simplified server-side-rendering applications, the general incompatibility of NodeJS server packages (e.g. in the express ecosystem) with FAB's V8 runtime makes this a challenge.

That said, converting NextJS's "serverless" output, which is still very NodeJS-y, to run on FABs proves that it is possible. In lieu of better documentation here, the best way to understand how that works is to look at the code or get in touch