Add JSDoc

The intent is to ultimately have the documentation published to
doc.wikimedia.org. This change is based on:

I have added some linkMap entries for ArrayBuffer and Promise type to
prevents warnings such as:

WARNING: Unknown link ArrayBuffer in Class: Client

The doc can be generated using npm run doc (expected by our CI) which
would results in doc generated under ./docs/.

We would need CI to be configured before this change get approved.

Bug: T236915
Depends-On: I187109f4840889246b288d766921aedc72950096
Change-Id: I092a688d3b146731270f3be5b5d89b57e7d1d8b7