docs: automate listing all stock/built-in types for typed extensions

A major problem with our documentation is the user does not know what types are available for all of the typed extension points. Obviously we can't know all custom extensions and all bets are off if the user is doing a custom build, but we can ignore those cases because those users won't have any issues.

For everyone else, I think we should:
1) Dump out all extensions in the stock build (either do this with bazel ahead of time, or somehow dump it out of the final exe). This is a map of extension type/category/link to docs, etc.
2) Automate the documentation so all typed_extensions are printed with docs listing all stock types, as well as links to relevant docs, as well as sample config.