automatically start server for jest (#26206)

* reinstate

* start server manually

* routing tests too

* skip more

* sleep more and fail if not 200

* use e2etest for content/ too

* automatically start server for jest

* does this work?

* feedbacked

* rename things

* getting it to work

* add dev dependency

* install the right version

* don't need to start that

* fix package lock

* update readme about it

* feedbacked

.github/workflows/browser-test.yml

@@ -59,5 +59,8 @@ jobs:
           path: .next/cache
           key: ${{ runner.os }}-nextjs-${{ hashFiles('package*.json') }}
 
+      - name: Run build script
+        run: npm run build
+
       - name: Run browser-test
         run: npm run browser-test