Hidden Typing & Read Receipts (#2230)

* add hide activity toggle

* stop sending/receiving typing status

* send private read receipt when setting toggle is activated

* prevent showing read-receipt when feature toggle in on

src/app/features/room/RoomViewFollowing.tsx

@@ -24,6 +24,10 @@ import { useRoomEventReaders } from '../../hooks/useRoomEventReaders';
 import { EventReaders } from '../../components/event-readers';
 import { stopPropagation } from '../../utils/keyboard';
 
+export function RoomViewFollowingPlaceholder() {
+  return <div className={css.RoomViewFollowingPlaceholder} />;
+}
+
 export type RoomViewFollowingProps = {
   room: Room;
 };