Fix default module highlight

Use subcategory model index to find the good module to update. Previous implementation worked for almost every case, but if you have different weight for submodules, updated module data was not the good one

sidebar/SidebarMode.cpp

@@ -579,7 +579,8 @@ void SidebarMode::updateDefaults()
     Q_ASSERT(item);
     // If subcategory exist update from subcategory
     if (!item->children().isEmpty()) {
-        item = item->child(d->activeSubCategoryRow);
+        auto subCateogryIdx = d->subCategoryModel->index(d->activeSubCategoryRow, 0);
+        item = subCateogryIdx.data(Qt::UserRole).value<MenuItem*>();
     }
     item->updateDefaultIndicator();