Add basic CI/CD functionality

This MR adds a basic CD/CD pipeline, which validates the top-level pipeline.cwl workflow with an example input.

.gitlab-ci.yml

 default:
-  image: $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG
+  image: 
+    name: $CI_REGISTRY_IMAGE/ci-build-runner:$CI_COMMIT_REF_SLUG
+    pull_policy: [always]
 
 workflow:
   rules: