[wip] Replace VS Code with Code OSS (wording for error message)

> 
> - `test-incompatible-positron-version.vsix` ⚠️ **_(should it say Code OSS instead of VS Code?)_**
> 
> <img width="385" height="83" alt="Image" src="https://github.com/user-attachments/assets/113936e5-a2a2-4cc6-925a-beecafa6b0fc" />
> 


 _Originally posted by @rodrigosf672 in [#11322](https://github.com/posit-dev/positron/issues/11322#issuecomment-3807309636)_