Add Workbench name as Tab item tooltip

In cases where the user's font is large or the Workbench name is long,
the new, narrower sidebar may not display the entire workbench name. To
address those cases, the tooltip for the element is now also set to the
workbench name. Thanks to Github user @marioalexis84 for the suggestion.

src/Gui/DlgPreferencesImp.cpp

@@ -126,6 +126,7 @@ QTabWidget* DlgPreferencesImp::createTabForGroup(const std::string &groupName)
     QListWidgetItem* item = new QListWidgetItem(ui->listBox);
     item->setData(GroupNameRole, QVariant(groupNameQString));
     item->setText(QObject::tr(groupNameQString.toLatin1()));
+    item->setToolTip(QObject::tr(groupNameQString.toLatin1()));
     std::string fileName = groupName;
     for (auto & ch : fileName) {
         if (ch == ' ') ch = '_';