Show the auto selected model name in the chat immediately after choosing

[MurzNN]

VS Code motivates us to use the "Auto" option for the Copilot model selection by 10% discount, which is great!

But very often it chooses the wrong model, not that I expect to be selected automatically. But to get to know the currently used model, I need to wait for the real response from the model, because intermediate responses like thinking and reading files - do not show the model name.

In result, I have to wait too long to understand that the automatically selected model is bad, and restart the request with the manually chosen model.

To resolve this issue, please show in the chat the automatically selected model name immediately when they got selected.

[MurzNN]

Also, would be great to see the reasoning why the auto mode chooses this specific model for the current request. It will give more understanding of how the auto mode chooses the model (now it looks like just magic 😉), and make this tool more popular for advanced developers.