fix: reject empty versionId query parameter in object actions

S3 returns `InvalidArgument` when an object action receives a `versionId` query parameter with no value. The gateway silently treated it as an unversioned request instead.

Added a shared `versionId` validation helper and apply it to the object actions that accept the parameter, so malformed requests are rejected up front rather than reaching the backend.

tests/integration/DeleteObject.go

@@ -383,3 +383,7 @@ func DeleteObject_expected_bucket_owner(s *S3Conf) error {
 		return err
 	})
 }
+
+func DeleteObject_empty_version_id(s *S3Conf) error {
+	return testEmptyVersionId(s, "DeleteObject_empty_version_id", http.MethodDelete, "", nil)
+}