Investigate user state change notifications

[blagoev]

JS has something like this

currentUser.addListener(handleUserEventChange);

const handleUserEventChange = () => {
  if (currentUser) {
    if (originalAccessToken !== currentUser.accessToken) {
      originalAccessToken = currentUser.accessToken;
    }
    switch (currentUser.state) {
      // @ts-expect-error
      case "LoggedIn": // Bug to be fixed: Literal is documented as 'active'
      // @ts-expect-error
      case 'LoggedOut': // Bug to be fixed: Literal is documented as 'logged-out'
        Logger.info(`User (id: ${currentUser.id}) has been logged out.`);
        resetUser();
      // break;
      // @ts-expect-error
      case 'Removed': // Bug to be fixed: Literal is documented as 'removed'
        Logger.info(`User (id: ${currentUser.id}) has been removed from the app.`);
        resetUser();
      default:
        break;
    }
  }
};

Consider adding a change stream in Dart for user state changesd