This cleans up attach a little bit, and moves it out of the container package. Really `AttachStream` is a method on `*stream.Config`, so moved if from a package level function to one bound to `Config`. In addition, uses a config struct rather than passing around tons and tons of arguments. Signed-off-by: Brian Goff <cpuguy83@gmail.com> Upstream-commit: 2ddec97545f4c5834cfbc163c0168ce1d5826ba2 Component: engine