Move the GraphVisualization wrapper

[OskarDamkjaer]

I found that using anywidget makes the interaction with React /javascript much cleaner and less hacky. To avoid breaking the public API, render is still there return  creating HTML, which i implemented by creating a tiny anywidget wrapper in plain html

I also added a new render_widget is there as a new alternative for 2 way data binding with the visualisation, as well as a GraphWidget export.

The PR is quite large 😅 and I've annotated best I can where I'm uncertain.

There's some open questions that'd be good to discuss:

• The default anywidget builds just use one folder (instead python-wrapper & js-applet) It seem cleaner & simpler to me, but it was a bigger change than what I wanted to do without discussing it first
• It also uses tooling to rebuild the js parts, to avoid commiting the built assets. Are we interested in doing that?
• How do we do with documentation of the new widget? Could it even make sense to do a major version and break the API? Or maybe we leave it as a separate entrypoint until it's "proven itself"?
• I'd love to get some reality checks some of the changes to python/integrations with other data sources. Some guidance/chats on how I best test manually/automatically would be good
• Is there a good way I can test out how this change would work in production/in a deployed mode, so I can verify I don't make unintended breaking changes?
• I don't see the integration tests running on PR, why not?

[FlorentinD]

Thanks for your PR!

I think we can reduce the breaking changes a bit.
Couple of suggestions and questions. For the python parts, I can also try to apply some of them.

I would also put a link to https://storybook-components-build.appspot.com/?path=/story/components-graph-visualization--default for reference in the graph-widget.tsx file.

I think before merging the PR, we should change:

[x] default coloring changed (fixable by setting the color in python if not set initially)
[x] Zoom in/out button missing (fixable) -- EDIT: i just didnt see the buttons
[x] Fix hierarchical layout
[x] Set correct caption on the node

On the zoom in/out, i dont get yet why the storybook example has the buttons but its not referenced in the code