Add Gitlab CI integration

Added .gitlab-ci.yml file and fixed most of the issues reported.

Given that we're getting warnings and not errors, we can merge this as it is and try to fix the remaining issues in followup issues to avoid conflicts.

This looks great to me! Nice to get those phpcs issues tidied up and protect future work from having problems.

Thanks for the updates. Context for adding the toolbar dependency: https://drupal.slack.com/archives/C7AB68LJV/p1705497926909629

We'll file a follow up to decouple toolbar completely.

Fixed. Thank you!!

Automatically closed - issue fixed for 2 weeks with no activity.