Move large examples / examples with code that belongs in separate files / notebook to separate repo

[timkpaine]

Large notebooks, for example, can increase the size of our repo substantially, so we should do something with these.

Separately, some of the larger notebook examples might do better in .py files where they can be linted/tested better

[melissawm]

Another option is to use text-based notebooks (see https://myst-nb.readthedocs.io/en/latest/authoring/text-notebooks.html)