✅(e2e) test the pdf export of the impress app

Add a test to check the pdf export of the
impress app.
It intercept the download of the PDF and
read its content.
We can assert that the template is correctly
rendered, and that the pad text is present as
well.

.github/workflows/impress-frontend.yml

@@ -137,6 +137,10 @@ jobs:
         run: |
           make migrate
 
+      - name: Add dummy data
+        run: |
+          make demo FLUSH_ARGS='--no-input'
+
       - name: Install Playwright Browsers
         run: cd src/frontend/apps/e2e && yarn install