introduce new IncrementalPublisher

= iterate only through completed items
= remove extra ticks by making the publisher manage changes to its state synchronously.
= use children array instead of promises to manage hierarchy
= have IncrementalPublisher instantiate new IncrementalDataRecords

= The new publisher sometimes cause an empty `{ hasNext: false }` to be emitted. In particular, because the publisher is faster than it was, it may emit a stream result before the stream's asynchronous iterator has completed.
= The new publisher may sometimes reduce the number of `{ hasNext: false }` records that are emitted. For example, when errors on the initial result filter all subsequent results, this now happens synchronously, and so the publisher knows immediately that there are no subsequent results, such that there is no need for an empty final payload.