Merge branch 'jt/port-ci-whitespace-check-to-gitlab'

The "whitespace check" task that was enabled for GitHub Actions CI
has been ported to GitLab CI.

* jt/port-ci-whitespace-check-to-gitlab:
  gitlab-ci: add whitespace error check
  ci: make the whitespace report optional
  ci: separate whitespace check script
  github-ci: fix link to whitespace error
  ci: pre-collapse GitLab CI sections

.github/workflows/check-whitespace.yml

@@ -26,66 +26,7 @@ jobs:
     - name: git log --check
       id: check_out
       run: |
-        baseSha=${{github.event.pull_request.base.sha}}
-        problems=()
-        commit=
-        commitText=
-        commitTextmd=
-        goodparent=
-        while read dash sha etc
-        do
-          case "${dash}" in
-          "---")
-            if test -z "${commit}"
-            then
-              goodparent=${sha}
-            fi
-            commit="${sha}"
-            commitText="${sha} ${etc}"
-            commitTextmd="[${sha}](https://github.com/${{ github.repository }}/commit/${sha}) ${etc}"
-            ;;
-          "")
-            ;;
-          *)
-            if test -n "${commit}"
-            then
-              problems+=("1) --- ${commitTextmd}")
-              echo ""
-              echo "--- ${commitText}"
-              commit=
-            fi
-            case "${dash}" in
-            *:[1-9]*:) # contains file and line number information
-              dashend=${dash#*:}
-              problems+=("[${dash}](https://github.com/${{ github.repository }}/blob/${{github.event.pull_request.head.ref}}/${dash%%:*}#L${dashend%:}) ${sha} ${etc}")
-              ;;
-            *)
-              problems+=("\`${dash} ${sha} ${etc}\`")
-              ;;
-            esac
-            echo "${dash} ${sha} ${etc}"
-            ;;
-          esac
-        done <<< $(git log --check --pretty=format:"---% h% s" ${baseSha}..)
-
-        if test ${#problems[*]} -gt 0
-        then
-          if test -z "${commit}"
-          then
-            goodparent=${baseSha: 0:7}
-          fi
-          echo "🛑 Please review the Summary output for further information."
-          echo "### :x: A whitespace issue was found in one or more of the commits." >$GITHUB_STEP_SUMMARY
-          echo "" >>$GITHUB_STEP_SUMMARY
-          echo "Run these commands to correct the problem:" >>$GITHUB_STEP_SUMMARY
-          echo "1. \`git rebase --whitespace=fix ${goodparent}\`" >>$GITHUB_STEP_SUMMARY
-          echo "1. \`git push --force\`" >>$GITHUB_STEP_SUMMARY
-          echo " " >>$GITHUB_STEP_SUMMARY
-          echo "Errors:" >>$GITHUB_STEP_SUMMARY
-          for i in "${problems[@]}"
-          do
-            echo "${i}" >>$GITHUB_STEP_SUMMARY
-          done
-
-          exit 2
-        fi
+        ./ci/check-whitespace.sh \
+          "${{github.event.pull_request.base.sha}}" \
+          "$GITHUB_STEP_SUMMARY" \
+          "https://github.com/${{github.repository}}"