Add None to PsesLogLevel enum

So that the extension can start when logging is disabled.

Fixes PowerShell/vscode-powershell#4735.

Author: andyleejordan

src/PowerShellEditorServices.Hosting/Configuration/HostLogger.cs

@@ -26,6 +26,7 @@ public enum PsesLogLevel
         Normal = 2,
         Warning = 3,
         Error = 4,
+        None = 5
     }
 
     /// <summary>