[AVM Module Issue]: avm/res/web/site support for linux function app flex consumption plan

### Check for previous/existing GitHub issues

- [x] I have checked for previous/existing GitHub issues

### Issue Type?

Feature Request

### Module Name

avm/res/web/site

### (Optional) Module Version

0.11.1

### Description

When I try to deploy a linux function app that uses flex consumption plan I get the following error:

```json
{
"code": "DeploymentFailed",
"target": "/subscriptions/{mysubscription}/resourceGroups/{myresourcegroup}/providers/Microsoft.Resources/deployments/functionAppDeployment",
"message": "At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.",
"details": [
{
"code": "InternalServerError",
"message": "There was an unexpected InternalServerError. Please try again later. x-ms-correlation-request-id: 03719248-ff76-4bac-aeb6-32f8cd6e0334"
}
]
}
```

My function app uses a private vnet to communicate with its storage.

### (Optional) Correlation Id

03719248-ff76-4bac-aeb6-32f8cd6e0334