chore: Reintroduce build, test and upload stages

.gitlab-ci.yml

 image: openjdk:11-jdk
 stages:
+  - build
+  - test
   - deploy
+  - upload
 
 variables:
   COMMON_CONFIG_REMOTE: https://root:$CONFIG_ACCESS_TOKEN@$CI_SERVER_HOST/VIPS/vips-common-config.git
@@ -31,6 +34,20 @@ before_script:
   - apt-get update -y && apt-get install -y python && apt-get install -y rsync openssh-client
   - "python build_pom_with_models.py"
 
+build:
+  stage: build
+  script:
+    - "./mvnw $MAVEN_POM_WITH_MODELS $MAVEN_CLI_OPTS $MAVEN_OPTS package -DskipTests"
+  tags:
+    - vips-java
+
+test:
+  stage: test
+  script:
+    - "./mvnw $MAVEN_POM_WITH_MODELS $MAVEN_CLI_OPTS $MAVEN_OPTS test"
+  tags:
+    - vips-java
+
 deploy-to-staging:
   stage: deploy
   script:
@@ -58,3 +75,87 @@ deploy-to-staging:
   environment:
     name: staging
     url: https://vipscore02test.nibio.no
+
+upload-snapshot:
+  stage: upload
+  script:
+    - export VERSION=$(./mvnw $MAVEN_POM_WITH_MODELS $MAVEN_CLI_OPTS $MAVEN_OPTS --batch-mode --no-transfer-progress --non-recursive help:evaluate -Dexpression=project.version | grep -v "\[.*")
+    - if ! [[ $VERSION =~ .*SNAPSHOT ]]; then
+      echo "Version '$VERSION' is not SNAPSHOT"; exit 1;
+      fi
+    - "./mvnw $MAVEN_POM_WITH_MODELS $MAVEN_CLI_OPTS $MAVEN_OPTS deploy -DskipTests"
+  tags:
+    - vips-java
+  rules:
+    - if: "$CI_COMMIT_REF_NAME == $MAIN_BRANCH"
+
+deploy-to-production:
+  stage: deploy
+  script:
+    - echo "NOT IMPLEMENTED"
+  tags:
+    - vips-java
+  only:
+    - release
+  environment:
+    name: production
+    url: https://vipscore02.nibio.no
+
+upload-and-tag-release:
+  stage: upload
+  script:
+    # Use access token given by CI/CD variable ACCESS_TOKEN to authenticate
+    - &authenticate
+      - export NEW_REPO_URL=https://root:$ACCESS_TOKEN@$CI_SERVER_HOST/$CI_PROJECT_PATH.git
+      - git remote set-url --push origin $NEW_REPO_URL
+      - git fetch origin --prune --prune-tags
+
+    # Checkout release branch
+    - &checkout_release
+      - git stash -a
+      - git checkout $RELEASE_BRANCH
+      - git reset --hard origin/$RELEASE_BRANCH
+      - git stash pop
+
+    # Set release version and deploy. Commit, tag and push.
+    - &release_and_tag # Change version in pom.xml - build new pom_with_models.xml
+      - "./mvnw $MAVEN_CLI_OPTS $MAVEN_OPTS validate -DremoveSnapshot"
+      - "python build_pom_with_models.py"
+      - export RELEASE_VERSION=$(./mvnw $MAVEN_POM_WITH_MODELS $MAVEN_CLI_OPTS $MAVEN_OPTS --batch-mode --no-transfer-progress --non-recursive help:evaluate -Dexpression=project.version | grep -v "\[.*")
+      - echo "New version in release '$RELEASE_VERSION'"
+      - export RELEASE_TAG="v${RELEASE_VERSION}"
+      - echo "Release tag '$RELEASE_TAG'"
+      - export EXISTING_TAGS=$(git ls-remote --tags origin | cut -f 2 | grep "refs/tags/$RELEASE_TAG$")
+      - echo "Existing tags '$EXISTING_TAGS'"
+      - if [ -n "$EXISTING_TAGS" ]; then
+        echo "Tag $RELEASE_TAG already exists"; exit 1;
+        fi
+      - "./mvnw $MAVEN_POM_WITH_MODELS $MAVEN_CLI_OPTS $MAVEN_OPTS deploy -DskipTests"
+      - git add pom.xml
+      - git commit -m "[ci skip] Set release version ${RELEASE_VERSION}"
+      - git tag -a $RELEASE_TAG -m "Tag release ${RELEASE_TAG}"
+      - git push origin $RELEASE_TAG
+      - git push origin $RELEASE_BRANCH
+
+    # Checkout main branch
+    - &checkout_main
+      - git stash -a
+      - git checkout $MAIN_BRANCH
+      - git reset --hard origin/$MAIN_BRANCH
+      - git stash pop
+
+    # Merge release branch, bump patch version, push commits.
+    - &merge_and_bump
+      - git merge -m "[ci skip] Merge branch '${RELEASE_BRANCH}' into ${MAIN_BRANCH}" --no-ff $RELEASE_BRANCH
+      # Change version in pom.xml - build new pom_with_models.xml
+      - "./mvnw $MAVEN_CLI_OPTS $MAVEN_OPTS validate -DbumpPatch"
+      - "python build_pom_with_models.py"
+      - export SNAPSHOT_VERSION=$(./mvnw $MAVEN_POM_WITH_MODELS $MAVEN_CLI_OPTS $MAVEN_OPTS --batch-mode --no-transfer-progress --non-recursive help:evaluate -Dexpression=project.version | grep -v "\[.*")
+      - echo "New version in main '$SNAPSHOT_VERSION'"
+      - git add pom.xml
+      - git commit -m "[ci skip] Set snapshot version ${SNAPSHOT_VERSION}"
+      - git push origin $MAIN_BRANCH
+  tags:
+    - vips-java
+  rules:
+    - if: "$CI_COMMIT_REF_NAME == $RELEASE_BRANCH"