Store Broadcaster and FeeEstimator on MonitorUpdatingPersister.
`MonitorUpdatingPersister` does not currently correctly archive
monitors because it neglects any unapplied updates. In order to start
applying these updates, the archiving methods will require access to
instances of `BroadcasterInterface` and `FeeEstimator`.
This commit requires that the `MonitorUpdatingPersister` be
instantiated with those instances, obviating the need for passing
them around, and laying the foundation for the following commit.