Allow multiple workers to write to receipts stream. (#16432)

changelog.d/16432.feature

synapse/config/workers.py

synapse/handlers/appservice.py

synapse/handlers/initial_sync.py

synapse/handlers/receipts.py

synapse/handlers/sync.py

synapse/notifier.py

synapse/replication/tcp/client.py

synapse/storage/databases/main/receipts.py

synapse/storage/databases/main/relations.py

...schema/main/delta/83/03_instance_name_receipts.sql.sqlite

synapse/streams/events.py

synapse/types/__init__.py

tests/handlers/test_appservice.py

tests/replication/test_sharded_receipts.py