Create example app for Alive API

[NicolasFussberger]

Depends-On: #229

What

Create a new example app that showcases the Alive API of the launch_manager.

Acceptance Criteria (DoD)

New example app showcasing the alive API

How

• Example app to be put under https://github.com/eclipse-score/lifecycle/tree/main/examples
• Create new folder cpp_supervised_app_simple for the app
• The app roughly looks like this:

    score::mw::lifecycle::Alive alive("instance");

    // report Running state
    // ...

    // Report alive notifications
    while(!exitRequested) {
        alive.ReportAlive();
        std::this_thread::sleep_for(std::chrono::milliseconds(<Sleep-Time>));
    }

    return 0;
}

• Maybe pass the via CLI (e.g. "-s ")
• Setup signal handling for handling SIGTERM
• Report Running state using lifecycle client
• Report alive notifications in a look until shutdown is requested
• Add the new example app to the existing demo configuration https://github.com/eclipse-score/lifecycle/blob/main/examples/demo_verification/lifecycle_demo_test.json and make sure everything still works