getUsers method
Retrieve all users from the database.
Implementation
Future<List<UserModel>> getUsers() async {
final retrieveUserlist = instance.httpsCallable('retrieveUserlist');
final HttpsCallableResult<dynamic> userList = await retrieveUserlist();
final List<dynamic> usersJson = userList.data as List<dynamic>;
return usersJson
.map((json) => UserModel.fromJson(prepareJson(json as Map)))
.toList();
}