Added restoration of blank tab

Blank tab is now being tracked for tab restoration on startup.

src/kiwixapp.cpp

@@ -207,6 +207,9 @@ void KiwixApp::restoreTabs()
     {
       for (const auto &zimUrl : tabsToOpen)
       {
+        if (zimUrl.isEmpty())
+          getTabWidget()->createNewTab(true, true);
+        else
           openUrl(QUrl(zimUrl));
       }
     }

src/tabbar.cpp

@@ -163,6 +163,7 @@ ZimView* TabBar::createNewTab(bool setCurrent, bool nextToCurrentTab)
     connect(tab, &ZimView::webActionEnabledChanged,
             this, &TabBar::onWebviewHistoryActionChanged);
 
+    KiwixApp::instance()->saveListOfOpenTabs();
     return tab;
 }