Question: Is jupyterlab always required as a dependency? If so, why is it not listed as one?

I've found that jupyterlab is required when running: `nbdev_export && nbdev_clean && nbdev_trust`

Also, the docs state:

> Note that nbdev must be installed into the same Python environment that you use for both Jupyter and your project.

However, jupyterlab isn't explicitly listed as a requirement. Why not? Are there use cases where one doesn't need it? Having it as requirement would make installation easier for everyone.

Start by inspecting nbdev's dependency metadata and the implementations behind `nbdev_export`, `nbdev_clean`, and `nbdev_trust`. Check whether each command requires JupyterLab, then compare that behavior with the installation and environment guidance in the documentation. Done means clearly establishing the dependency requirement and updating the relevant metadata or explanation.

Written by the indexing model from the issue text.