az kusto database-principal-assignment create doesn't work with role UnrestrictedViewers

### Kusto

I'm trying to use the ``az kusto database-principal-assignment`` command to grant *UnrestrictedViewers* access but I get the following error: ``(BadRequest) Database principal role is invalid. Please provide valid database principal role (Admin, Viewer, User, etc.).``.

Here is the full command for context:

```
$me = az ad signed-in-user show --query objectId

az kusto database-principal-assignment create `
--cluster-name "mycluster" `
--database-name "mydatabase"`
--principal-id $me `
--principal-type User `
--role UnrestrictedViewers `
--principal-assignment-name "assignmentname" `
--resource-group "myrg"
```

Running ``az kusto database-principal-assignment create -h`` shows UnrestrictedViewers as one of the allowed values for role, but looks like the server rejects it.