[jupyterhub] Add jupyterlab iframe extension

jupyterhub/base/Dockerfile

@@ -56,6 +56,10 @@ RUN python${PYTHON_VERSION} -m pip install jupyterlab_code_formatter==1.3.8 && \
 RUN python${PYTHON_VERSION} -m pip install jupyterlab-git && \
     python${PYTHON_VERSION} -m jupyter lab build
 
+RUN python${PYTHON_VERSION} -m pip install jupyterlab_iframe && \
+    python${PYTHON_VERSION} -m jupyter labextension install jupyterlab_iframe && \
+    python${PYTHON_VERSION} -m jupyter serverextension enable --py jupyterlab_iframe
+
 RUN mkdir -p /usr/local/venv && \
     python${PYTHON_VERSION} -m venv /usr/local/venv/default && \
     . /usr/local/venv/default/bin/activate && \