message: Fix URL previews being enabled when room first created
  We didn't update whether URL previews should be enabled when encryption
  was enabled in a room, so when you create a room (or enable encryption)
  it starts off with URL previews using the setting for non-e2e rooms
  untilyou switch rooms / refresh.
diff: @@ -944,6 +944,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
  if (ev.getType() === "m.room.encryption") {
  this.updateE2EStatus(room);
  + this.updatePreviewUrlVisibility(room);
  }
  // ignore anything but real-time updates at the end of the room:
  