Scalog Replication

Replication sequence

1. Client sends messages to primary nodes
- network_manager receives the message and direct the message to cxl_manager to write to cxl

2. Primary sends gRPC request to next replica in chain (replica is (broker_id +1)%num_total_brokers)
- network_manager calls gRPC to replica node (disk_manager/[scalog_replication_manager.cc)
- Make a separate thread for gRPC send (poll from folly::MPMC_queue). network_manager.cc to post replication request (size, pointer, dest addr) to replication_thread_queue

3. Replicas write requested write to its disk
- Scalog_replication_manager.cc writes the message to its disk (log-structured)