test(devtools): revive cypress tests (#61972)

Previously these tests would run automatically when Angular DevTools lived in another repo. These files have continued to live here but have not been running automatically on each PR.

Now, these test files have been revived to run properly with our changes since the repo merge. This is a first step to reviving our e2e testing.

Next steps include writing cypress tests for new features like Injector Graph, Router tree, signals visualizations, etc.

PR Close #61972

.github/workflows/pr.yml

@@ -60,6 +60,13 @@ jobs:
         run: yarn devtools:test
       - name: Test build
         run: yarn devtools:build:chrome
+      - name: Cypress run
+        uses: cypress-io/github-action@6c143abc292aa835d827652c2ea025d098311070 # v6.10.1
+        with:
+          command: yarn devtools:test:e2e
+          start: yarn bazel run //devtools/src:devserver
+          wait-on: 'http://localhost:4200'
+          wait-on-timeout: 300
 
   test:
     runs-on: ubuntu-latest-8core