Instead of assuming that we should use the OSC 9 progress messages
whenever we run on serenity, add a show-progress=[true|false] option.
This lets us avoid seeing esc sequence spam in GitHub Actions logs.
Build a new version of Serenity in CI that doesn't have all the debug
symbols on, or we'd be waiting a very long time to boot.
Insert a TestRunner entry into SystemServer.ini that will run a shell
script that runs tests in /bin and /usr/Tests and shuts down the system
in the new self-test boot mode. Also make sure enough basic services are
started in self-test such that the tests will actually run properly.
