VSCode support

[hyiip]

Thanks for continuing this amazing repository.
Previous qgrid does not support vscode's jupyter notebook (quantopian/qgrid#309) as the npm version was outdated. But given that qgridnext can be considered as a new package, it should be possible to upload the js file to npm such that we can use the ipywidgets on vscode.

[zhihanyue]

Qgridnext appears to work properly on vscode's jupyter notebook.