Merge branch 'develop' into babolivier/msc3026

changelog.d/9636.bugfix

changelog.d/9640.misc

changelog.d/9643.feature

changelog.d/9645.misc

changelog.d/9647.misc

scripts-dev/federation_client.py

synapse/api/constants.py

synapse/config/experimental.py

synapse/federation/federation_server.py

synapse/federation/sender/per_destination_queue.py

synapse/handlers/set_password.py

synapse/handlers/space_summary.py

synapse/rest/admin/users.py

synapse/rest/client/v1/room.py

synapse/server.py

synapse/storage/databases/main/registration.py

tests/federation/test_federation_catch_up.py

tests/rest/admin/test_user.py