docs: New API reference visual treatment (#4494)

* Content-complete on ApolloServer constructor and EngineReportingOptions updates
* Fix some broken links
* Fix some broken headers
* Incorporate #4426 change and merge segmented tables
* Use HTML-md-hybrid table to enable custom styles
* Use new API reference front matter and update some headers
* Use two-column field table layout
* Intentionally leave old EngineReportingOptions format,
  for more optimal formatting, since it's going away soon anyway.
* Put experimental AS constructor option in its own table
* Re-apply lost Fastify context signature changes (from #3895)
* Re-apply lost spelling correction (from #4473)

Co-authored-by: Stephen Barlow <[email protected]>
Co-authored-by: Jesse Rosenberger <[email protected]>