Support any process writing to cache invalidation stream. (#7436)

changelog.d/7436.misc

docs/tcp_replication.md

scripts/synapse_port_db

synapse/replication/slave/storage/_base.py

synapse/replication/slave/storage/account_data.py

synapse/replication/slave/storage/deviceinbox.py

synapse/replication/slave/storage/devices.py

synapse/replication/slave/storage/events.py

synapse/replication/slave/storage/groups.py

synapse/replication/slave/storage/presence.py

synapse/replication/slave/storage/push_rule.py

synapse/replication/slave/storage/pushers.py

synapse/replication/slave/storage/receipts.py

synapse/replication/slave/storage/room.py

synapse/replication/tcp/client.py

synapse/replication/tcp/commands.py

synapse/replication/tcp/handler.py

synapse/replication/tcp/resource.py

synapse/replication/tcp/streams/_base.py

synapse/replication/tcp/streams/events.py