[Segment Replication] Missing a request orchestrator to process replication events.

[mch2]

Similar to PeerRecoveryTargetService that is used during peer recovery, Segment Replication needs a service class to orchestrate replication events for all shards on a node. This allows us to receive a new checkpoint and start a new replication event in a separate thread.

This is similar to the SegmentReplicationReplicaService class implemented in feature branch but. needs to be revisited and PR'd to main.

Similar to PeerRecoveryTargetService, replication events will need a target class implementation that is kicked off to start the event. Refactoring here would open the door for a SegmentReplicationTarget implementation that can be invoked from the service.