[BUG] `Microsoft.ContainerRegistry` @ `2023-07-01` - `IdentityProperties` for `CredentialSets` define identity modes not supported by the API

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/aa4ba9eb0ab21268118c11052b081ff5d2e01e4d/specification/containerregistry/resource-manager/Microsoft.ContainerRegistry/stable/2023-07-01/containerregistry.json#L2754-L2756

### API Spec version

2023-07-01

### Describe the bug

The spec defines support for `UserAssigned` and `SystemAssigned, UserAssigned` identities for `CredentialSets`, but when trying to create a Credential Set with either of these identity modes an API error is returned:

```
{
"error": {
"code": "CannotSetResourceIdentity",
"message": "Resource type 'Microsoft.ContainerRegistry/registries/credentialSets' does not support creation of 'UserAssigned' resource identity. The supported types are 'SystemAssigned'."
}
}
```

```
{
"error": {
"code": "CannotSetResourceIdentity",
"message": "Resource type 'Microsoft.ContainerRegistry/registries/credentialSets' does not support creation of 'SystemAssigned, UserAssigned' resource identity. The supported types are 'SystemAssigned'."
}
}
```

### Expected behavior

That only `SystemAssigned` is defined for the `type` field in `IdentityProperties`, or the API is updated to support these modes.

### Actual behavior

Identity types are defined that are not supported by the API

### Reproduction Steps

Try and create a Credential Set resource with `UserAssigned` or `SystemAssigned, UserAssigned` Identity via the API

### Environment

_No response_