Update stock status on CSV Product import according to quantity

If the is_in_stock field is not present in a particular row in the
CSV file and the qty field is set to 0, the default is_in_stock value
is overriden from 1 to 0.

Author: Kristian Charbonneau

app/code/Magento/CatalogImportExport/Model/Import/Product.php

@@ -2972,6 +2972,10 @@ private function formatStockDataForRow(array $rowData): array
         $stockItemDo = $this->stockRegistry->getStockItem($row['product_id'], $row['website_id']);
         $existStockData = $stockItemDo->getData();
 
+        if (isset($rowData['qty']) && $rowData['qty'] == 0 && !isset($rowData['is_in_stock'])) {
+            $rowData['is_in_stock'] = 0;
+        }
+
         $row = array_merge(
             $this->defaultStockData,
             array_intersect_key($existStockData, $this->defaultStockData),