feat: Implement sub-room functionality

- Added support for sub-rooms in the SpaceHierarchy component, allowing rooms to have nested child rooms.
- Introduced UnjoinedSubRoomItem component to display unjoined sub-rooms with a join button.
- Created SubRooms settings page for managing sub-rooms, including adding and removing sub-rooms.
- Updated RoomNavItem to include options for creating sub-rooms.
- Enhanced room fetching logic to filter out sub-rooms from the main room list.
- Added hooks for managing sub-rooms state and permissions.
- Updated relevant state management to handle sub-room creation and association with parent rooms.

src/app/features/room-nav/index.ts

@@ -1,3 +1,4 @@
 export * from './RoomNavItem';
 export * from './RoomNavCategoryButton';
 export * from './CallParticipantsIndicator';
+export * from './UnjoinedSubRoomItem';