Add Symfony Console command to allow running cron updates via console and by a separate user, for defense-in-depth

Not adding sprint tag right now as I figure out what else needs to be done for #3284443: Enable unattended updates

core/scripts/db-tools.php might be a example of how to write a php file to invoke a console command.

\Drupal\Core\Command\ServerCommand::boot might be a example of how to create a command the boots

There is on todo left pointing to this issue in \Drupal\Tests\automatic_updates\Kernel\TestCronUpdateStage::runTerminalUpdateCommand()

// @todo Determine if the terminal command can be run in kernel tests when
    //   the Drush dependency is removed in https://drupal.org/i/3360485.
    //   Drush\TestTraits\DrushTestTrait only works with functional tests.

We don't actually need to run the command in kernel tests as of now so we could just remove the todo. We if we could run the command in kernel tests then we could probably convert StatusCheckFailureEmailTest back to kernel test which was before #3357969: For web server dependent unattended updates run the entire life cycle in a separate process that will not be affected by hosting time limits but that is not super important as it does work as a functional.

Either way we need to remove the todo

Looks good!

RTBC, hoping both branches pass