Merge branch 'develop' into babolivier/mark_unread

changelog.d/7648.bugfix

changelog.d/7688.bugfix

changelog.d/7689.bugfix

changelog.d/7692.misc

synapse/api/auth.py

synapse/api/errors.py

synapse/app/generic_worker.py

synapse/app/homeserver.py

synapse/events/__init__.py

synapse/events/snapshot.py

synapse/federation/federation_base.py

synapse/federation/federation_server.py

synapse/federation/send_queue.py

synapse/federation/sender/__init__.py

synapse/handlers/appservice.py

synapse/handlers/auth.py

synapse/handlers/device.py

synapse/handlers/e2e_keys.py

synapse/handlers/e2e_room_keys.py

synapse/handlers/federation.py