feat: add pyodide

[NickCrews]

Hi! I'm not sure exactly how this would fit into the current stack, but I don't see an issue here so I thought I'd bring it up here.

I have been loving using this to document my project: my examples now serve as walkthroughs, howtos, tests, and are intuitive to author. However, a key party of my library is interactive widgets. Currently, because there is no actual python kernel, the outputs from these cells just show the plaintext mimetype text such as VBox(children=(Dropdown(description='Column:', index=3, options=('record_id', 'label_true', 'name_true', 'name…. It would be better if my users could actually interact with the widgets, run things, etc as they explore my lib.

HoloViz's nbsite project manages to use pyodide to give you a runnable kernel in the built site. How hard would it be to get this working for this project? I could write some PRs, but I'm not sure where to start.