Use VS Code API to contribute view to the secondary sidebar

VS Code PM here 👋

VS Code now allows extensions to contribute views to the secondary sidebar
https://github.com/microsoft/vscode/issues/151681

I notice that in your docs you mention to users to manually move the view. With this API this will no longer be necessery, you can programmatically do it.

Keep in mind that this API is still in proposed state, and we aim to finalize it start of October. So it would be great if you try out the API - let us know if it works for you, and once it is final you should be able to use it.

<img width="1075" height="222" alt="Image" src="https://github.com/user-attachments/assets/39205a40-86e4-4bb7-b259-8d3885eb6362" />

fyi @embirico