Issue #3464819: Add gitlab ci file

Closes #3464819

.gitlab-ci.yml

+include:
+  ################
+  # DrupalCI includes:
+  # As long as you include this, any future includes added by the Drupal Association will be accessible to your pipelines automatically.
+  # View these include files at https://git.drupalcode.org/project/gitlab_templates/
+  ################
+  - project: $_GITLAB_TEMPLATES_REPO
+    ref: $_GITLAB_TEMPLATES_REF
+    file:
+      - '/includes/include.drupalci.main.yml'
+      - '/includes/include.drupalci.variables.yml'
+      - '/includes/include.drupalci.workflows.yml'