New Drupal 9 appliance

[JedMeister]

Now that Drupal 9 stable has been released (June 3, 2020) we should create a new Drupal9 appliance.

Unlike previous Drupal major version bumps, Drupal9 has much less significant changes, so the Drupal8 appliance build code probably won't need a ton of adjustment, but there will likely be some tweaks required.

The only thing that is blocking currently is the fact that drupal console doesn't currently support Drupal 9. Although we could disable drupal console for now and push ahead with a new Drupal9 appliance (after all, Drupal 9 has been stable for 3 months and the issue still exists...).

[JedMeister]

Unblocking by removing drupal console for now... We can reinstate it once it's compatible with Drupal 9.

[OnGle]

Drupal9 is complete https://github.com/turnkeylinux-apps/drupal9