Fix crash when opening notification settings with no account by making sure that the keyword model doesn't try to update the noficiation settings when there is no active connection.

Also make sure that ability to add a keyword or change the global notiifcaiton state is disabled without an active connection as these will cause the same crash.

src/keywordnotificationrulemodel.cpp

@@ -15,7 +15,9 @@
 KeywordNotificationRuleModel::KeywordNotificationRuleModel(QObject *parent)
     : QAbstractListModel(parent)
 {
-    controllerConnectionChanged();
+    if (Controller::instance().activeConnection()) {
+        controllerConnectionChanged();
+    }
     connect(&Controller::instance(), &Controller::activeConnectionChanged, this, &KeywordNotificationRuleModel::controllerConnectionChanged);
 }