Experiment: try to use AnyWidget for periodic table widget and ipywidget-extend

[unkcpz]

AnyWidget allow to create flexible JS widgets without the needed to maintain and host a repo. If the component existed, the widget can be easily created and embedded.
If all works as expected, we can get rid of the periodic table widget dependency by using the https://www.npmjs.com/package/mc-react-ptable-materials-grid to have the UI uniform with MC3D/ACWF app on materials cloud.

Also able to simply the maintenance of the dependencies by having extended dropdown widget in the repo.