Allow to (re)generate keys via drush or UI

Oh, your keys don't exist anymore then? Crap, yeah, the UI doesn't check that, I'll try to fix that.

I've committed code that adds a drush command, but that won't work if you are not on the latest dev version, so underneath is the code that should work if you add that to ActivityPubCommands.php:

  /**
   * Generates keys for a name.
   *
   * @param $name
   *
   * @command activitypub:generate-keys
   */
  public function generateKeys($name) {
    $this->logger()->notice('Generating keys for ' . $name);
    /** @var \Drupal\activitypub\Services\SignatureInterface $signature */
    $signature = \Drupal::service('activitypub.signature');
    if ($signature->generateKeys($name)) {
      $this->logger()->notice('Keys generated successfully');
    }
    else {
      $this->logger()->notice('Error generating keys, please check the logs for more details');
    }
  }

To run: drush activitypub:generate-keys {name}
name is the name of the actor you configured at user/1/activitypub/settings , without the domain. e.g. in my case, it's just 'swentel'.

This has been committed to dev.

It should be save to install the dev version which allows you to (re)generate the keys via the ui too (on user/x/activitypub/settings)
Or use the drush command in the previous comment.

However, do not enable the api modules, that's still in very active development!