For TS 5.0, we're making some major build changes and package cleanups stemming from our conversion from namespaces to modules. protocol.d.ts is one file I'm trying to eliminate, as it's tricky to produce in the new build. See also:

• Can we stop shipping typescriptServices.js? TypeScript#50758
• Remove typescriptServices.{js,d.ts}, protocol.d.ts, typescript_standalone.d.ts TypeScript#51026
• Module conversion tracking issue / notes TypeScript#49332

Rather than using this a d.ts file, we can depend on the same namespace as exported by tsserverlibrary instead, a file that is definitely not going away.

This actually reveals a couple of interesting things:

• The ambient protocol namespace was being used in a couple places where it shouldn't have been.
• Two types needed to be reexported via the protocol, implying that our protocol is not self-contained. That's something to address on the TS side, but nothing new.