Add JupyterLab Extensions to Local Instructions

[jlperla]

Subset of #653
@arnavs see this for the hubs. I tested on destkop

On a desktop

conda install -c conda-forge nodejs
pip install jupyterlab-quickopen
jupyter labextension install @jupyterlab/toc  --no-build
jupyter labextension install @parente/jupyterlab-quickopen  --no-build
jupyter labextension install @jupyter-widgets/jupyterlab-manager --no-build
jupyter lab build --dev-build=False
npm cache clean --force

Can this stuff be done within julia miniconda? Dunno.

[arnavs]

@jlperla Just to confirm, at this point we are only installing this stuff? Or do you also want me to try plugging it into the actual hub

[arnavs]

OK, seems to work out of the box. I've added it to the hubs.

Renaming this and moving to 1.2 (just a guess) for when we are ready to put this in the instructions.