add variation of Stream.iterate() that's finite

Stream.iterate() and Stream.generate() are factories for infinite streams. It would be nice if there were a similar stream factory methods that could return finite streams.

We are also considering something like Stream.takeWhile() -- see JDK-8071597 -- but this will terminate a stream based on a predicate on the stream value itself, not on some changed state of the stream source (e.g., reaching EOF).