feat(sliding_sync): Add m.room.join_rules to the required state

We need the join rules state event to prevent the SDK from assuming a room with an unknown (as in, not loaded) join rule is public.

crates/matrix-sdk-ui/src/room_list_service/mod.rs

@@ -88,6 +88,7 @@ const DEFAULT_REQUIRED_STATE: &[(StateEventType, &str)] = &[
     (StateEventType::RoomCanonicalAlias, ""),
     (StateEventType::RoomPowerLevels, ""),
     (StateEventType::CallMember, "*"),
+    (StateEventType::RoomJoinRules, ""),
 ];
 
 /// The default `required_state` constant value for sliding sync room