Move the presence handler out of the Handlers object

synapse/handlers/__init__.py

synapse/handlers/events.py

synapse/handlers/message.py

synapse/handlers/presence.py

synapse/handlers/sync.py

synapse/replication/resource.py

synapse/rest/client/v1/presence.py

synapse/rest/client/v1/room.py

synapse/rest/client/v2_alpha/receipts.py

synapse/rest/client/v2_alpha/sync.py

synapse/server.py

tests/replication/test_resource.py