Add model wrapper to other Retiarii examples (#3838)

examples/notebooks/Retiarii_example_multi-trial_NAS.ipynb

@@ -109,7 +109,9 @@
    "source": [
     "import torch.nn.functional as F\n",
     "import nni.retiarii.nn.pytorch as nn\n",
+    "from nni.retiarii import model_wrapper\n",
     "\n",
+    "@model_wrapper\n",
     "class Net(nn.Module):\n",
     "    def __init__(self):\n",
     "        super(Net, self).__init__()\n",

examples/notebooks/tabular_data_classification_in_AML.ipynb

@@ -127,7 +127,9 @@
    "source": [
     "import nni.retiarii.nn.pytorch as nn\n",
     "import torch.nn.functional as F\n",
+    "from nni.retiarii import model_wrapper\n",
     "\n",
+    "@model_wrapper\n",
     "class Net(nn.Module):\n",
     "\n",
     "    def __init__(self, input_size):\n",

test/retiarii_test/darts/darts_model.py

 from collections import OrderedDict
+from nni.retiarii.serializer import model_wrapper
 from typing import (List, Optional)
 
 import torch
@@ -7,7 +8,7 @@ import torch.nn as torch_nn
 
 import ops
 import nni.retiarii.nn.pytorch as nn
-from nni.retiarii import basic_unit
+from nni.retiarii import basic_unit, model_wrapper
 
 @basic_unit
 class AuxiliaryHead(nn.Module):
@@ -98,6 +99,7 @@ class Cell(nn.Module):
         output = torch.cat(new_tensors, dim=1)
         return output
 
+@model_wrapper
 class CNN(nn.Module):
 
     def __init__(self, input_size, in_channels, channels, n_classes, n_layers, n_nodes=4,