Add Jupyter Lab support

[JulianWgs]

Is your feature request related to a problem? Please describe. I want to use this awesome extension in Jupyter Lab, too!

Describe the solution you'd like Make it possible to install this extension in Jupyter Lab.

Describe alternatives you've considered Jupyter Lab is the future of the Jupyter project. Sooner or later every extension needs to be converted.

Additional context Awesome project!

[CermakM]

Thank you!

I am well aware that I am gonna have to port that eventually and I also have some pretty neat ideas which are only possible in Jupyter Lab to be realized, so I am actually looking forward to it. I am just a bit short of time, but there are already some preparations in progress.

Stay tuned!

Cheers, Marek

[CermakM]

Help wanted: The first step here is to implement https://github.com/CermakM/jupyter-require JupyterLab support.