Update visualizer code

dataset_infos.json

@@ -0,0 +1,13 @@
+{
+  "default": {
+    "features": null,
+    "splits": {},
+    "download_size": 1234,
+    "dataset_size": 5678,
+    "config_name": "default",
+    "description": "",
+    "csv": {
+      "delimiter": ";"
+    }
+  }
+}