Merge branch 'develop' into matthew/filter_members

changelog.d/3350.misc

changelog.d/3586.misc

changelog.d/3587.misc

changelog.d/3595.misc

changelog.d/3597.feature

changelog.d/3601.bugfix

changelog.d/3604.feature

changelog.d/3605.bugfix

changelog.d/3606.misc

changelog.d/3607.bugfix

synapse/app/client_reader.py

synapse/app/homeserver.py

synapse/app/synchrotron.py

synapse/events/snapshot.py

synapse/federation/federation_server.py

synapse/groups/attestations.py

synapse/handlers/federation.py

synapse/handlers/profile.py

synapse/handlers/room.py

synapse/replication/tcp/client.py