.Net: fix: AutorRole.Developer missing (#13310)

1. Why is this change required?
AuthorRole.Developer was missing from the ModelDiagnostic.RoleToEventMap
configuration.
This was causing OpenTelemetry diagnostic to throw exceptions when the
Developer role was used


  2. What problem does it solve?
 Fixes the dictionary so exception are no longer occurring

  3. What scenario does it contribute to?
 Enabling open telemetry and using developer messages

  4. If it fixes an open issue, please link to the issue here.
#13302

Author: sciutand

dotnet/src/InternalUtilities/src/Diagnostics/ModelDiagnostics.cs

@@ -651,13 +651,15 @@ private static class ModelDiagnosticsTags
         public const string UserMessage = "gen_ai.user.message";
         public const string AssistantMessage = "gen_ai.assistant.message";
         public const string ToolMessage = "gen_ai.tool.message";
+        public const string DeveloperMessage = "gen_ai.tool.developer";
         public const string Choice = "gen_ai.choice";
         public static readonly Dictionary<AuthorRole, string> RoleToEventMap = new()
             {
                 { AuthorRole.System, SystemMessage },
                 { AuthorRole.User, UserMessage },
                 { AuthorRole.Assistant, AssistantMessage },
-                { AuthorRole.Tool, ToolMessage }
+                { AuthorRole.Tool, ToolMessage },
+                { AuthorRole.Developer, DeveloperMessage }
             };
     }
     # endregion