Make CI create comment with link to HTML artifacts (ros2#4564)

Signed-off-by: Christophe Bedard <[email protected]>

.github/workflows/test.yml

@@ -62,8 +62,30 @@ jobs:
         uses: actions/upload-artifact@v4
         id: artifact-upload-step
         with:
-          name: html-artifacts
+          name: html-artifacts-${{ github.event.pull_request.number }}
           path: build/html
           retention-days: 30 # default 90
           compression-level: 9 # maximum compression, default 6
           if-no-files-found: error # 'warn' or 'ignore' are also available, defaults to `warn`
+
+      - name: Find HTML artifacts link comment
+        uses: peter-evans/find-comment@v3
+        id: find-comment
+        with:
+          issue-number: ${{ github.event.pull_request.number }}
+          comment-author: 'github-actions[bot]'
+          body-includes: "HTML artifacts:"
+
+      - name: Create or update HTML artifacts link comment
+        uses: peter-evans/create-or-update-comment@v4
+        with:
+          comment-id: ${{ steps.find-comment.outputs.comment-id }}
+          issue-number: ${{ github.event.pull_request.number }}
+          body: |
+            HTML artifacts: ${{ steps.artifact-upload-step.outputs.artifact-url }}.
+
+            To view the resulting site:
+            1. Click on the above link to download the artifacts archive
+            2. Extract it
+            3. Open `html-artifacts-${{ github.event.pull_request.number }}/index.html` in your favorite browser
+          edit-mode: replace