(re-)add gitlab ci pipeline

.gitlab-ci.yml

+stages:
+  - build-project
+  - build-container
+
+variables:
+  KANIKO_BUILD_IMAGENAME: admin-backend
+
+build-project:
+  stage: build-project
+  before_script: []
+  script:
+    - echo "Building app"
+    - yarn
+    # - echo "REACT_APP_API_URL=https://oas-api.initdevelopment.com/api/v1" > .env
+    # - echo "EXTEND_ESLINT=true" >> .env
+    - yarn build
+    - mv build web-build
+    - echo "Build successful"
+  artifacts:
+    expire_in: 1 hour
+    name: web-build
+    paths:
+      - web-build
+
+build-container:
+  stage: build-container
+  image:
+    # We need a shell to provide the registry credentials, so we need to use the
+    # kaniko debug image (https://github.com/GoogleContainerTools/kaniko#debug-image)
+    name: gcr.io/kaniko-project/executor:debug
+    entrypoint: [""]
+  script:
+    - cp deployment/Dockerfile web-build
+    - cp deployment/nginx.conf web-build
+    - cd web-build
+    - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
+    - /kaniko/executor --cache=true --context ${CI_PROJECT_DIR}/ --dockerfile ${CI_PROJECT_DIR}/web-build/Dockerfile --destination ${CI_REGISTRY_IMAGE}/${KANIKO_BUILD_IMAGENAME}:${CI_COMMIT_REF_NAME}
+