Include m.room.create in invite_room_state for Spaces (#9710)

changelog.d/9710.feature

+Experimental Spaces support: include `m.room.create` in the room state sent with room-invites.

synapse/config/api.py

@@ -88,6 +88,10 @@ class ApiConfig(Config):
         if not room_prejoin_state_config.get("disable_default_event_types"):
             yield from _DEFAULT_PREJOIN_STATE_TYPES
 
+            if self.spaces_enabled:
+                # MSC1772 suggests adding m.room.create to the prejoin state
+                yield EventTypes.Create
+
         yield from room_prejoin_state_config.get("additional_event_types", [])