No option to turn on "Backup/restore over virtual network" option for App Service Backup commands

### Describe the bug

At present, there is no option in either `az webapp config backup create` or `az webapp config backup update` azcli commands to set the "Backup/restore over virtual network integration" option in the Custom Backup section of a Windows App Service.


This is causing the created Custom Backup to fail since target storage account has firewall enabled and access is restricted inside the vnet.

### Related command

az webapp config backup update
az webapp config backup create

### Errors

No Errors but created Custom backup does not have "Backup/restore over virtual network integration" option Enabled which is causing backup to fail since target storage account has firewall enabled and access is restricted to the Vnet.

### Issue script & Debug output

N/A

### Expected behavior

There should be an option to set "Backup/restore over virtual network integration" to either True or False from azcli commands.

### Environment Summary

azure-cli 2.55.0 *

core 2.55.0 *
telemetry 1.1.0

Extensions:
interactive 0.5.3

Dependencies:
msal 1.24.0b2
azure-mgmt-resource 23.1.0b2

Python location 'C:\Program Files\Microsoft SDKs\Azure\CLI2\python.exe'
Extensions directory 'C:\Users\asd\.azure\cliextensions'

Python (Windows) 3.11.5 (tags/v3.11.5:cce6ba9, Aug 24 2023, 14:38:34) [MSC v.1936 64 bit (AMD64)]

Legal docs and information: aka.ms/AzureCliLegal

### Additional context

_No response_