Generated documentation was using the base directory & package.json for all libraries. Fixed the directories & package jsons to use.

It must have worked at one point, bc the doc sites have some classes as direct links.

I'm not sure npm test passes - it's timing out on my toaster.

To test:

• On main, run npm run docs, then open one of the generated index.htmls. You will see "Google APIs Node.js Client"
• On this branch, run npm run docs, then open a generated index.html. You should see the name of the API at the top, and the "classes" link on the left should show & work.
• Verify that the URL paths for the "Classes" are the same as the originals.

Fixes #3460 and #3405 🦕