Support for testitem runner

It would be nice to have the testitem runner support of the normal julia-vscode extension (https://github.com/julia-vscode/TestItems.jl); at the moment they go undetected: 

<img width="459" height="238" alt="Image" src="https://github.com/user-attachments/assets/b8d2d698-3ba8-47d6-a6d1-5ac9d711409e" />