Add Gitlab CI

Added in the MR!

Thanks @majorrobot. I'll try to give this a review this weekend.

Thank you @majorrobot. I can see the GitLab CI run. Hi @jaydarnell, probably will need a follow-up ticket to fix phpcs and related issues.

Thanks @majorrobot and @dmundra. I've merged this work and will start working on fixes for the items identified by circleCI.

Thank you @jaydarnell

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