Adding a Google Drive File Explorer Widget

[rickmcgeer]

This has two pieces, a front end and a back end. The general idea is that people should be able to explore GDrive and easily transfer files between GDrive and their Galyleo Hub Drive.
I think this is basically another Lively-based Jupyter extension -- we should decide if it's JupyterLab or a standalone application, a la RStudio or VSCode. It's a lot easier to do a standalone application that just works from the filesystem (@m-hemmings has done such an amazing job with RStudio and VSCode that this is a live possibility).
I think this could be done fairly easily. The Drive API seems to have the functionality we need, so the issue will be getting a UI. See the Drive API here: https://developers.google.com/drive/api/guides/about-sdk.
There are two choices for the UI. The first is to use the JupyterLab file explorer UI, which we can, with effort, integrate with. It may be that it'll be easier than the Galyleo integration, because the FileManager classes seem to be a lot more stable than the Editor classes.
The second choice for the UI is to write our own Lively file explorer application, and plug this in as a separate Hub application with a different icon on the launcher. This may be the shorter path; there's an open-source file explorer library here: https://github.com/cubiclesoft/js-fileexplorer.
As always on JavaScript matters, I defer to @merryman