.Net: Bug: Open Telemetry throws for AuthorRole Developer messages

[oli-ideally]

Describe the bug
Enabling Open Telemetry throws and error for AuthorRole.Developer messages as they are not present in:
https://github.com/microsoft/semantic-kernel/blob/cf9a5f21f74782fddfada1d934088fbff6cc24b9/dotnet/src/InternalUtilities/src/Diagnostics/ModelDiagnostics.cs#L655C63-L655C77

To Reproduce
Steps to reproduce the behavior:

1. Enable Open Telemetry
2. Add a developer type message
3. See error

Expected behavior
Developer type messages should be mapped correctly within ModelDiagnostics for Open Telemetry

Screenshots

Platform

• Language: C#
• Source: main branch
• AI model: --
• IDE: --
• OS: --