fix: Add build for staff dashboard

The staff dashboard wasn't getting built into the Docker image so it is currently broken
in Kubernetes environments. This adds the missing steps to the build.

Author: blarghmatey

Dockerfile

@@ -68,8 +68,11 @@ FROM node:17.9 AS node
 COPY --from=code /src /src
 WORKDIR /src
 
+ENV NODE_ENV=production
 RUN yarn workspace mitx-online-public install --immutable && \
-    yarn workspace mitx-online-public run build
+    yarn workspace mitx-online-public run build && \
+    yarn workspace mitx-online-staff-dashboard install --immutable && \
+    yarn workspace mitx-online-staff-dashboard run build
 
 FROM code AS django-server