[ci] add yml file for pipeline config

.gitlab-ci.yml

+default:
+  image: registry.dune-project.org/docker/ci/dune:2.7-debian-11-gcc-9-20
+
+cache:
+  key: ${CI_COMMIT_REF_SLUG}
+  paths:
+    - dep_modules
+
+stages:
+  - build
+  - test
+
+# rules for build & test:
+# - pipelines are built for commits to master, tags, merge requests
+# - Within merge requests, we require manual trigger of the build stage
+#   to start off the pipeline
+.build_rules:
+  rules:
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
+    - if: $CI_PIPELINE_SOURCE=="pipeline"
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
+      when: manual
+
+.test_rules:
+  rules:
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
+    - if: $CI_PIPELINE_SOURCE=="pipeline"
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
+
+build lecture:
+  extends: .build_rules
+  stage: build
+  before_script:
+    - mkdir -p dep_modules; cd dep_modules
+    - git clone -b releases/2.7 https://gitlab.dune-project.org/extensions/dune-foamgrid.git
+    - git clone -b releases/2.7 https://gitlab.dune-project.org/extensions/dune-alugrid.git
+    - git clone -b master https://git.iws.uni-stuttgart.de/dumux-repositories/dumux.git
+    - dunecontrol --opts=/duneci/dune.opts --only=dune-foamgrid all
+    - dunecontrol --opts=/duneci/dune.opts --only=dune-alugrid all
+    - dunecontrol --opts=/duneci/dune.opts --only=dumux all
+    - cd ..
+  script:
+    - cd ..
+    - dunecontrol --opts=/duneci/dune.opts --only=dumux-lecture all
+    - cd dumux-lecture/build-cmake
+    - make -j 8 build_tests
+  artifacts:
+    paths:
+      - build-cmake
+    expire_in: 3 hours
+
+test lecture:
+  extends: .test_rules
+  stage: test
+  script:
+    - cd build-cmake
+    - duneci-ctest -j4 --no-tests=error
+  needs:
+    - job: build lecture
+      artifacts: true