build: ensure that non-Tutor systems handle copy-node-modules.sh

Two fixes:

* In the (in-repo, non-Tutor) Dockerfile, add copy-node-modules.sh
  before `npm install`, since it is needed by the new postinstall hook.

* In paver/assets.py, run copy-node-modules.sh for backwards com-
  patibility, just for cases where `SKIP_NPM_INSTALL` is enabled
  (which would prevent our new postinstall hook from running
  automatically!). We will deprecate the paver asset commands all at
  once once the new non-paver stuff is 100% working.

Dockerfile

@@ -115,9 +115,16 @@ COPY requirements requirements
 RUN pip install -r requirements/pip.txt
 RUN pip install -r requirements/edx/base.txt
 
-# Install node and node modules
+# Install node and npm
 RUN nodeenv /edx/app/edxapp/nodeenv --node=16.14.0 --prebuilt
 RUN npm install -g [email protected]
+
+# This script is used by an npm post-install hook.
+# We copy it into the image now so that it will be available when we run `npm install` in the next step.
+# The script itself will copy certain modules into some uber-legacy parts of edx-platform which still use RequireJS.
+COPY scripts/copy-node-modules.sh scripts/copy-node-modules.sh
+
+# Install node modules
 COPY package.json package.json
 COPY package-lock.json package-lock.json
 RUN npm set progress=false && npm ci

pavelib/assets.py

@@ -611,8 +611,7 @@ def process_npm_assets():
     """
     Process vendor libraries installed via NPM.
     """
-    print("\t\tProcessing NPM assets is now done automatically in an npm post-install hook.")
-    print("\t\tThis function is now a no-op.")
+    sh('scripts/copy-node-modules.sh')
 
 
 @task