Allow running sendToDevice on workers (#9044)

changelog.d/9044.feature

scripts/synapse_port_db

synapse/app/generic_worker.py

synapse/config/workers.py

synapse/handlers/devicemessage.py

synapse/replication/slave/storage/deviceinbox.py

synapse/replication/tcp/handler.py

synapse/storage/databases/main/__init__.py

synapse/storage/databases/main/deviceinbox.py

...databases/main/schema/delta/59/02shard_send_to_device.sql

...ema/delta/59/03shard_send_to_device_sequence.sql.postgres