refac: repository updates, image attachment and deletes report the domain not-found error for an unknown id, the same for articles, users and images, and the test fakes stop returning GORM errors

internal/infrastructure/persistence/repositories/notFound.go

@@ -12,3 +12,13 @@ func mapNotFoundErr(err error, sentinel error) error {
 	}
 	return err
 }
+
+func deleteOrNotFound(result *gorm.DB, sentinel error) error {
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return sentinel
+	}
+	return nil
+}