Notebooks: Support User-Installed Kernels (#10194)

* Fixes for attach to. Still need to update cache

* Don't have jupyter hardcoded

* Handle DOTNET_ROOT env var

* Fix on load

* Put behind feature flag

* Cleanup

* Error check

* PR feedback

extensions/notebook/src/jupyter/jupyterServerInstallation.ts

@@ -332,6 +332,12 @@ export class JupyterServerInstallation implements IJupyterServerInstallation {
 		let env = Object.assign({}, process.env);
 		delete env['Path']; // Delete extra 'Path' variable for Windows, just in case.
 		env['PATH'] = this.pythonEnvVarPath;
+
+		// We don't want Jupyter to know about DOTNET_ROOT, as it's been modified by the liveshare experience
+		// Without this, won't be able to find the ASP.NET bits
+		if (process.env['DOTNET_ROOT']) {
+			delete env['DOTNET_ROOT'];
+		}
 		this.execOptions = {
 			env: env
 		};