Revive and rework tooling around exported API

[davidjgoss]

🤔 What's changed?

• Upgrade api-extractor to the latest and turn it back on for the api entry point
• Also turn it on, with more forgiving configuration, for the root entry point
• Fix a bunch of issues (missing exports etc) flagged by api-extractor
• Remove api-documenter and the docs it previously generated
• Add typedoc and have it deploy to GitHub Pages on every commit to main
• Generally improve some documentation and types

⚡️ What's your motivation?

We added api-extractor and api-documenter a while ago for the new /api entry point, but then disabled them due to some weird compatibility issues with hybrid packages and/or protobuf.

As we add more to the /api entry point soon for plugins, and also look to shrink the exports from the root entry point, we'll get a lot of value from api-extractor as it's very good at finding issues that would cause a poor developer experience for consumers. So I wanted to revive this.

api-documenter on the other hand produces output which is not quite so usable/accessible as an HTML site, and it also doesn't handle multiple entry points. typedoc is better suited on both fronts for us. So I wanted to switch to this.

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, documentation etc. without changing behaviour)
• 🐛 Bug fix (non-breaking change which fixes a defect)

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

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[coveralls]

coverage: 98.379% (-0.002%) from 98.381%
when pulling 6289319 on revive-api-extractor
into 0fbe487 on main.