[microsoft.web/sites]: Missing property `vnetBackupRestoreEnabled` for `sites` and child resource `sites/slots`

### Resource Type

`microsoft.web/sites` and `microsoft.web/sites/slots`

### Api Version

2022-09-01

### Issue Type

Missing property(s)

### Other Notes

`vnetBackupRestoreEnabled` is a valid property for read/write. It is missing from the documentations for [microsoft.web/sites](https://learn.microsoft.com/en-us/azure/templates/microsoft.web/2022-09-01/sites?pivots=deployment-language-bicep) and [microsoft.web/sites/slots](https://learn.microsoft.com/en-us/azure/templates/microsoft.web/2022-09-01/sites/slots?pivots=deployment-language-bicep).

It's also missing from the [public REST API Specs](https://github.com/Azure/azure-rest-api-specs/blob/main/specification/web/resource-manager/Microsoft.Web/stable/2023-01-01/WebApps.json)


### Bicep Repro

```bicep
resource app 'Microsoft.Web/sites@2022-09-01' = {
name: name
location: location
kind: kind
tags: tags
identity: identity
properties: {
serverFarmId: serverFarmResourceId
clientAffinityEnabled: clientAffinityEnabled
httpsOnly: httpsOnly
hostingEnvironmentProfile: !empty(appServiceEnvironmentResourceId) ? {
id: appServiceEnvironmentResourceId
} : null
storageAccountRequired: storageAccountRequired
keyVaultReferenceIdentity: !empty(keyVaultAccessIdentityResourceId) ? keyVaultAccessIdentityResourceId : null
virtualNetworkSubnetId: !empty(virtualNetworkSubnetId) ? virtualNetworkSubnetId : any(null)
siteConfig: siteConfig
clientCertEnabled: clientCertEnabled
clientCertExclusionPaths: !empty(clientCertExclusionPaths) ? clientCertExclusionPaths : null
clientCertMode: clientCertMode
cloningInfo: !empty(cloningInfo) ? cloningInfo : null
containerSize: containerSize != -1 ? containerSize : null
customDomainVerificationId: !empty(customDomainVerificationId) ? customDomainVerificationId : null
dailyMemoryTimeQuota: dailyMemoryTimeQuota != -1 ? dailyMemoryTimeQuota : null
enabled: enabled
hostNameSslStates: hostNameSslStates
hyperV: hyperV
redundancyMode: redundancyMode
publicNetworkAccess: !empty(publicNetworkAccess) ? any(publicNetworkAccess) : (!empty(privateEndpoints) ? 'Disabled' : 'Enabled')
vnetContentShareEnabled: vnetContentShareEnabled
vnetImagePullEnabled: vnetImagePullEnabled
vnetBackupRestoreEnabled: vnetBackupRestoreEnabled
vnetRouteAllEnabled: vnetRouteAllEnabled
scmSiteAlsoStopped: scmSiteAlsoStopped
}
}
```

### Confirm

- [X] I have read the troubleshooting guide and looked for duplicates.

Start by comparing the 2022-09-01 sites and sites/slots documentation with specification/web/resource-manager/Microsoft.Web/stable/2023-01-01/WebApps.json. Trace how the REST specification feeds the generated Bicep types and verify the property is available for read/write on both resources; the Bicep repro should then validate successfully.

Written by the indexing model from the issue text.