Allow build line list to be searched by IPN (#7442)

- Closes https://github.com/inventree/InvenTree/issues/7434

src/backend/InvenTree/build/api.py

@@ -380,6 +380,8 @@ class BuildLineList(BuildLineEndpoint, ListCreateAPI):
 
     search_fields = [
         'bom_item__sub_part__name',
+        'bom_item__sub_part__IPN',
+        'bom_item__sub_part__description',
         'bom_item__reference',
     ]