getUser method
- String id
override
    Retrieves a user based on the ID.
Implementation
@override
Future<ChatUserModel?> getUser(String id) {
  var user = users.firstWhere((element) => element.id == id);
  return Future.value(user);
}Retrieves a user based on the ID.
@override
Future<ChatUserModel?> getUser(String id) {
  var user = users.firstWhere((element) => element.id == id);
  return Future.value(user);
}