Include frontend deps when building in CI

.gitlab-ci.yml

 stages:
-  - build_content
+  - build_js
+  - build_html
   - build_image
 
-build_content:
-  stage: build_content
+build_js:
+  stage: build_js
+  image: node:14
+  script:
+    - npm install --dev
+    - make js
+  artifacts:
+    paths:
+      - theme/static/
+
+build_html:
+  stage: build_html
+  dependencies:
+    - build_js
   image: python:3
   script:
     - pip install -r requirements.txt
@@ -15,7 +28,7 @@ build_content:
 build_image:
   stage: build_image
   dependencies:
-    - build_content
+    - build_html
   image:
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]