Add data previewer

[alexhad6]

Could be a mime renderer for NetCDF files, or something like "Contextual Help" that previews the log file currently selected.

This would work by kernel messaging (see https://github.com/jupyterlab/extension-examples/tree/main/kernel-messaging) to plot using matplotlib.

[alexhad6]

Simple PDF viewer done in https://github.com/PainterQubits/jupyterlab-pdf-preview. This would be more advanced.