Automatic synchronization

Initial implementation of the auto synchronizer. This should be decently more efficient reducing the number of database, and network calls substantially. This later needs to be extended to server -> client synchronization, maybe some exponential backoff. As part of this PR every location with explicit backfilling was removed polycentric-react. The module Synchronizer depends on QueryManager. Note that QueryManager, and Synchronizer were added to ProcessHandle. I am aware that the UI currently passes around a manually constructed QueryManager. Ideally there is only ever one. So as of this PR there are two instances as changing that is a larger overhaul. The synchronizer will automatically handle new / removed servers, backfill on startup, backfill on new events ingested.