Switch InternalDataKind to use GetString instead of the default ToString to resolve difference in Enum serialization between .NET 6 and .NET 8.

Author: JakeRadMSFT

src/Microsoft.ML.Core/CommandLine/CmdParser.cs

@@ -10,6 +10,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Text;
+using Microsoft.ML.Data;
 using Microsoft.ML.Internal.Utilities;
 using Microsoft.ML.Runtime;
 
@@ -2015,6 +2016,10 @@ private void AppendSettingCore(IHostEnvironment env, StringBuilder sb, object va
                     var buffer = new StringBuilder();
                     sb.Append(GetString(env, value, buffer));
                 }
+                else if (value is InternalDataKind)
+                {
+                    sb.Append(((InternalDataKind)value).GetString());
+                }
                 else
                     sb.Append(value.ToString());
             }