fix: use id instead of SKU (#39)

Use entity_id in the WHERE clause instead of sku. This adjustment enhances the query's speed, especially when dealing with a large number of products.

During local testing, the export time decreased significantly from 50 minutes to just 8 minutes. Resulting in an increase in speed of 84%. This speed increase only seems to occur if you don't have all numbers as sku's.

Model/Write/Products/CollectionDecorator/StockData/SourceItemMapProvider.php

@@ -111,7 +111,7 @@ public function getStockItemMap(Collection|StockCollection $collection): array
             return [];
         }
 
-        $skus = $collection->getAllSkus();
+        $entityIds = $collection->getAllIds();
 
         $store = $collection->getStore();
         $sourceCodes = $this->getSourceCodesForStore($store);
@@ -159,7 +159,7 @@ public function getStockItemMap(Collection|StockCollection $collection): array
                 ->select()
                 ->from($stockItemTable)
                 ->reset('columns')
-                ->where("$stockItemTable.product_id IN (?)", $collection->getAllIds())
+                ->where("$stockItemTable.product_id IN (?)", $entityIds)
                 /*
                 $stock_id is in this case the default stock id (i.e. 1) this filter problably doesnt remove anything
                 but it is here just to be sure.
@@ -207,7 +207,7 @@ public function getStockItemMap(Collection|StockCollection $collection): array
                 'backorders',
             ]
         )
-        ->where("$productTableName.sku IN (?)", $skus)
+        ->where("$productTableName.entity_id IN (?)", $entityIds)
         ->columns(
             [
                 'product_entity_id' => "$productTableName.entity_id",