gitlab-ci: Fix the pipeline on forks

Our guidelines say that to contribute people should fork repositories,
but at the moment this gives them a broken pipeline.

Tweak things in a way that the main project triggers
tests/apertis-test-cases-web to collect and indirectly publish all the
release branches while forked repositories directly publish their own
branches via Pages for easier testing.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

.gitlab-ci.yml

@@ -21,8 +21,24 @@ render-pages:
     paths:
       - ${release}
 
+# the main project triggers tests/apertis-test-cases-web to collect and indirectly publish all the release branches
 deploy-pages:
   stage: deploy
   trigger:
     project: tests/apertis-test-cases-web
     branch: main
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "push" && $CI_PROJECT_PATH == "tests/apertis-test-cases"
+
+# forked repositories publish directly to Pages their own branches for easier testing
+pages:
+  stage: deploy
+  script:
+    - mv ${release} public/
+  rules:
+    - if: $CI_PROJECT_PATH == "tests/apertis-test-cases"
+      when: never
+    - if: $CI_PIPELINE_SOURCE == "push"
+  artifacts:
+    paths:
+      - public/