Documentation: Add all code examples to the docs

[GenevieveBuckley]

It would be good to ensure all the code examples are visible to users reading the online documentation at https://napari.org/magicgui/

The magicgui documentation has a section called "Examples" but it only contains three examples, when there are over twenty examples in the repository examples folder https://github.com/napari/magicgui/tree/main/examples.

Some of the examples in that folder (progress bars, tablular data, etc.) would likely be very useful for a wider range of people to know about.

Perhaps an automated or semi-automated solution could work to help build the docs? If it did nothing else other than include the scripts verbatim without any extra explanations, that would still be an improvement over having this content be effectively invisible to people viewing the docs instead of the repo.