`Http2ServerRequest#setTimeout` should return `this`

[rexagod]

http2.Http2ServerRequest.setTimeout should return this instead of void/undefined

It's the last thing in the TypeScript typings to fix:

Argument of type 'Http2ServerRequest' is not assignable to parameter of type 'IncomingMessage'.
  The types returned by 'setTimeout(...)' are incompatible between these types.
    Type 'void' is not assignable to type 'IncomingMessage'.ts(2345)

See:

• node/lib/_http_incoming.js

  Line 100 in 4678e44

  return this;

• node/lib/internal/http2/compat.js

  Line 416 in 4678e44

  this[kStream].setTimeout(msecs, callback);

Originally posted by @clshortfuse in #29829 (comment)