Fixes custom metrics SN-123 (#1442)

- Added annotation types to custom metrics
- removed confidence scores in the image prediction notebook for masks, since it is not supported
- changed the folder structure of the model diagnostic files

Author: ovalle15

examples/model_diagnostics/custom_metrics_basics.ipynb renamed to examples/model_experiments/model_diagnostics/custom_metrics_basics.ipynb

@@ -16,27 +16,17 @@
       "metadata": {},
       "source": [
         "<td>\n",
-        "<a href=\"https://colab.research.google.com/github/Labelbox/labelbox-python/blob/master/examples/model_diagnostics/custom_metrics_basics.ipynb\" target=\"_blank\"><img\n",
+        "<a href=\"https://colab.research.google.com/github/Labelbox/labelbox-python/blob/master/examples/model_experiments/model_diagnostics/custom_metrics_basics.ipynb\" target=\"_blank\"><img\n",
         "src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"></a>\n",
         "</td>\n",
         "\n",
         "<td>\n",
-        "<a href=\"https://github.com/Labelbox/labelbox-python/tree/master/examples/model_diagnostics/custom_metrics_basics.ipynb\" target=\"_blank\"><img\n",
+        "<a href=\"https://github.com/Labelbox/labelbox-python/tree/master/examples/model_experiments/model_diagnostics/custom_metrics_basics.ipynb\" target=\"_blank\"><img\n",
         "src=\"https://img.shields.io/badge/GitHub-100000?logo=github&logoColor=white\" alt=\"GitHub\"></a>\n",
         "</td>"
       ],
       "cell_type": "markdown"
     },
-    {
-      "metadata": {},
-      "source": [
-        "  \n",
-        "<td>\n",
-        "    <a target=\"_blank\" href=\"https://labelbox.com\" ><img src=\"https://labelbox.com/blog/content/images/2021/02/logo-v4.svg\" width=256/></a>\n",
-        "</td>"
-      ],
-      "cell_type": "markdown"
-    },
     {
       "metadata": {},
       "source": [