Split replication layer into two

synapse/app/homeserver.py

synapse/federation/federation_server.py

synapse/federation/transport/server.py

synapse/handlers/device.py

synapse/handlers/directory.py

synapse/handlers/e2e_keys.py

synapse/handlers/federation.py

synapse/handlers/presence.py

synapse/handlers/profile.py

synapse/handlers/room_list.py

synapse/handlers/room_member.py

synapse/server.py