Limit the number of styles shipped by default?

[krassowski]

Shipping all the styles might be suboptimal as the package weights ~10 MB. It is okay-ish for PyPI but ideally we would just depend on a package that distributes styles (to allow for more efficient cache, independent updates, etc). Also, we might not need to ship all the styles by default. We could use optional requirements to install all styles like pip install jupyterlab-citation-manager[all].