Remove the need to keep the stream around

[dvdsk]

Its a common footgun in using rodio. It should be possible to store the stream in the sink.

Remaining questions, does the stream need to be accessible when a sink is used? If so how? Does sink get a method to get the stream?

Implementation wise it seems like storing the stream in an Arc will work.

[PetrGlad]

Can Sink's output be not a stream but another source? Should they give some shared reference to the output stream in that case?

I would keep sink as simple as possible unless there is a compelling reason to add anything to it. It is a lot harder to remove things from API than to add them.