I extracted the AsAny code from two crates and put it into the as-any crate. This PR switches from the "custom" implementation to use the crate instead. Maybe, we should upstream the AnyQueueHandler into the reclutch main crate.
Perhaps downcasting could be constrained to types that implement DynQueueHandler, but that's up to you.
previous discussion: https://github.com/jazzfool/sinq/pull/2.