Add gitlab_templates pipeline file

The basic gitlab-ci.yml file works. I have set eslint, stylelint and phpcs to have allow_failure: false so that we can easily see what is wrong. I think this is OK in the first instance. Ready for review and commit. Then we can get the other issues running on pipelines to see how they go.

The phpunit pipeline job fails in the pipeline but passes OK on drupalCI. That will need some investigation, but should not stop the gitlab-ci file from being committed.

Will address the eslint findings in the javascript tickets.

Will need a follow up for the failing tests.

Created 📌 testUninstallPageFiltering fails in Gitlab pipeline Active for the failing phpunit test

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