TASK: Build both plugins during tests

Author: Sebobo

.github/workflows/tests.yml

@@ -48,8 +48,11 @@ jobs:
       - name: Install dependencies
         run: yarn
 
-      - name: Build sources
+      - name: Build main module
         run: yarn build:module
 
+      - name: Build secondary editor for Neos UI
+        run: yarn build:editor
+
       - name: Run TestCafe
         run: yarn test:github-actions