Can the panel preview tool be bundled with panel rather than pyviz_comms?

[itcarroll]

Is your feature request related to a problem? Please describe.

Despite the recent and very helpful update to the documentation, I was still unable to set up panel in separate jupyter and kernel environments without help. Repeating the claim I made on Discourse, I think the current documentation is incomplete if you want the panel preview tool to work with separated environments.

1. The environment (A) running jupyter lab needs panel (not just pyviz_comms) for the panel preview icon to work.
2. The environment (B) used as the notebook kernel needs nbconvert (not just panel) for the panel preview icon to work.

Describe the solution you'd like

I heartily support the separation of concerns between pyviz_comms and panel. I don't know how these things work, but is it possible to package the panel preview tool with panel? I would like to keep A uncluttered while allowing my jupyterhub users the ability to install and use panel in whatever B they create. If I install only pyviz_comms in A however, everyone gets that panel preview tool (and they'll click it, and be sad).

As for the second observation that B needs nbconvert. Is it possible to use the nbconvert from A but provide the --ExecutePreprocessor.kernel_name=B parameter?

Describe alternatives you've considered

1. more documentation about installing panel and pyviz_comms when using separate environments
2. configure pyviz_comms to only show the panel preview icon if panel is in the notebook kernel's environment