{AzureNetwork} fixes Azure#20256 Fix for applicationGatewayIpConfigurations, property (Azure#22875)

fixes Azure#20256

This swagger definition is defining property applicationGatewayIpConfigurations,

```
"applicationGatewayIpConfigurations": {
          "type": "array",
          "items": {
            "$ref": "./applicationGateway.json#/definitions/ApplicationGatewayIPConfiguration"
          },
          "description": "Application gateway IP configurations of virtual network resource."
        }
```
but actual rest api returned applicationGatewayIPConfigurations, the P is upper case while in swagger it is lower case.
```
{
  "name": "subnet-agw",
  "id": "/subscriptions/<sub-id>/resourceGroups/<rg-name>/providers/Microsoft.Network/virtualNetworks/<vnet-name>/subnets/subnet-agw",
  "properties": {
      "applicationGatewayIPConfigurations": [
          {
              "id": "/subscriptions/<sub-id>/resourceGroups/<rg-name>/providers/Microsoft.Network/applicationGateways/<agw-name>/gatewayIPConfigurations/appGatewayIpConfig"
          }
      ]
  },
  "type": "Microsoft.Network/virtualNetworks/subnets"
}
```
Please update correspondingly.

Author: navba-MSFT

specification/network/resource-manager/Microsoft.Network/stable/2022-09-01/virtualNetwork.json

@@ -1625,7 +1625,7 @@
             "modelAsString": true
           }
         },
-        "applicationGatewayIpConfigurations": {
+        "applicationGatewayIPConfigurations": {
           "type": "array",
           "items": {
             "$ref": "./applicationGateway.json#/definitions/ApplicationGatewayIPConfiguration"