gitlab-ci: Configure website build to be published via gitlab pages

On pushes to master publish the webpage (built in the 'website_job' job)
via gitlab pages. The 'pages' job uses the default image that gitlab
assumes as it's consuming artifacts from an existing job and naming
them properly.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

.gitlab-ci.yml

@@ -6,6 +6,7 @@ stages:
   - builds
   - integration_tests
   - sanity_checks
+  - pages
 
 .script_variables: &script_variables |
   export CCACHE_BASEDIR="$(pwd)"
@@ -85,6 +86,23 @@ website_job:
     NAME: almalinux-8
     TARGET_BASE_IMAGE: docker.io/library/almalinux:8
 
+# On push to master publish the website from 'website_job' via gitlab pages
+pages:
+  stage: pages
+  script:
+    - mv website public
+  dependencies:
+    - website_job
+  rules:
+    - if: '$CI_PROJECT_NAMESPACE == $RUN_UPSTREAM_NAMESPACE && $CI_PIPELINE_SOURCE == "push" && $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH'
+      when: on_success
+    - when: never
+  artifacts:
+    expose_as: 'pages'
+    name: 'pages'
+    paths:
+      - public
+
 .codestyle_job:
   stage: sanity_checks
   needs: