Add Live Code with JupyterLite kernel

[guenp]

I'd like to enable executable code cells in the static HTML assets, see: https://jupyterbook.org/en/stable/interactive/thebe.html, except using JupyterLite kernel instead of MyBinder.

[guenp]

Opened a PR here to set up Thebe: #69

[guenp]

Looks like sphinx-thebe does not support using a JupyterLite kernel instead of MyBinder: executablebooks/sphinx-thebe#27

[rossbar]

I'm very interested in this feature as well - I think it'd be a huge improvement to UX to have the execution live within the served page as opposed to the swap over to a different (e.g. jupyter lab) interface.

[guenp]

Agreed this would be a nice UX!

In the end what I think needs to happen to enable this is to render the HTML using thebe-lite (see https://jupyter-book.github.io/thebe/ and https://github.com/jupyter-book/thebe/tree/main/packages/lite). There are a few ways we can do this -- probably the easiest route is a contribution to sphinx-thebe, we'd need to update thebe_config to enable this Thebe configuration:

<script type="text/x-thebe-config">
{
    useBinder: false,
    useJupyterLite: true
}
</script>

as well as include all static thebe-lite assets (including the pyolite wheels).

Here's a screenshot of a quick demo based on just editing the static HTML generated by Sphinx:

Instead of clicking the "activate" button you'd hover over the spaceship and click "Live Code", which is then configured to activate JupyterLite instead of a Binder kernel.

Edit: Another thing that would be nice to add to the Launch (spaceship) button is an "open in JupyterLite" option