Add code CLI for collaborative working

Add code CLI to enable making a tunnel for collaborative working. Live Share does not seem to be supported on code-server, but with code CLI a tunnel can be made to share the workspace to share the files in real-time. There is no cursor sharing etc. but every guest has the possibility to execute an independent interactive mode window (jupyter server) with the environment of the host. The interactive mode has some issues on Live Share in our tests (depending on the host settings either hanging on the guest to start or not showing and sending the commands to the hosts directly). To make the tunnel the host has to execute in a shell: code tunnel and share the link in the form https://vscode.dev/tunnel/<machine_name>/<folder_name> from the output of the command.