message: Using GCSFile struct for tf_gcs_filesystem
diff: @@ -292,9 +292,9 @@ void NewRandomAccessFile(const TF_Filesystem* filesystem, const char* path,
  ParseGCSPath(path, false, &bucket, &object, status);
  if (TF_GetCode(status) != TF_OK) return;
  - auto gcs_client = static_cast<gcs::Client*>(filesystem->plugin_filesystem);
  + auto gcs_file = static_cast<GCSFile*>(filesystem->plugin_filesystem);
  file->plugin_file = new tf_random_access_file::GCSFile(
  - {std::move(bucket), std::move(object), gcs_client});
  + {std::move(bucket), std::move(object), &gcs_file->gcs_client});
  TF_SetStatus(status, TF_OK, "");
  }
  