Dedupe builtin/vX/util/*

[rvagg]

Similar to #286, almost everything in builtin/vX/util/* is duplicated and identical (apart from minor import reorgs) from v8 to v15. So we should just move them to the top level. The exception to this is the adt directory which can stay.

I'm not sure we even need to leave aliases in place, this could be a breaking change for the next major release. If a future state change adjusts any of these (e.g. FilterEstimate might grow a new field?) then we could do what we do with ActorV4 and ActorV5 or introduce a new package with a version, e.g. smoothing2.