Jupyterlab 4 compatible extension

Requires JupyterLab 4

The extension was originally written as a Lab 4 compatible extension, and then it was created as a Lab 3 compatible extension. This version is Lab 4 compatible but retains the features that were added to the Lab 3 instance.

v0.1.1

JupyterLab 3.x compatible

Full Changelog: https://github.com/mlhenderson/jupyterlab_wall/commits/v0.1.1