Add automatic TypeDoc generation to Functions SDK

[thechenky]

Description

Make it possible to autogenerate documentation by using TypeDoc on the Functions SDK repo. This version does not depend on the index.d.ts file, but instead uses /src as the source of truth. Note that the links are currently broken - it looks like the files are getting written out as just the object name instead of the full namespace. So instead of functions.analytics.AnalyticsEvent.html it's writing it out as AnalyticsEvent.html. If this is acceptable, I can change the paths in the toc file to unnest. I think this is probably from the differences between admin generating their doc from an index.d.ts file that preserves the hierarchies vs us generating from src/ files.

Code sample

To generate docs, run node docgen/generate-docs.js from the root directory.

[thechenky]

@hiranya911 this seems to work when generating from /src in the functions SDK, but it's not the nice hierarchy that I saw in admin. I'd love for these paths to be namespaced better but I suppose it doesn't matter since these paths just make the links work, right?

[thechenky]

@egilmorez @hiranya911 this is a work in progress but just wanted to get your take on this and how far away it is from looking ready. Mind taking a look and regenerating the docs on your machine to see if they look right? There's an issue with some links being broken that I can fix.

[egilmorez]

I have been pulling and trying this out as we go, and right now everything looks fine!

[thechenky]

@kevinajian @egilmorez this is now ready for review. I fixed the toc checks, so should now be in final state.

[egilmorez]

Looks great Diana! Thanks.