service metatag.generate_tag in Metatag 8

class: Drupal\metatag\Command\GenerateTagCommand
arguments:
  - '@metatag.manager'
  - '@metatag.tag_generator'
  - '@?console.extension_manager'
  - '@?console.string_converter'
  - '@?console.chain_queue'
  - '@console.validator'
tags:
  - { name: drupal.command }