init method
initializes initial values and configurations for the package
Implementation
void init(GlobalKey<NavigatorState> navKeyFromMainApp, String rootDomain,
{Function? newGetAtValueFromMainApp}) {
atClientManager = AtClientManager.getInstance();
currentAtSign = AtClientManager.getInstance().atClient.getCurrentAtSign();
initializeContactsService(rootDomain: rootDomain);
navKey = navKeyFromMainApp;
ROOT_DOMAIN = rootDomain;
startMonitor();
}