Run python script triggered by an menu entry

Hi Everyone,
I am a really newbie and I want to create a toolchain.
Therefore I used the Theia example and extended it with some menu entries and now I would like to fill the entries with life.
E.g. there is a project ( which I want to start by selecting a menu entry.
How can I do that?

Here is snippet:

registerCommands(commands: CommandRegistry): void {
commands.registerCommand(DevelopmentWorkplaceScenarioScenarioArchitect, {
    execute: () => {
        alert('This is a sample command!');

Instead of running the alert, I would like to execute this command: