Consider moving all the tutorial code to files, having not only the final version there #2247

At the moment only the final version of the tutorials is in the example folder, while the intermediate code is pasted into the rst files.

It would be nice to have all versions in code, so that lint and format tool etc could work on those too.

We could probably use examples/asgilook/versions/01_file.py, examples/asgilook/versions/02_file.py etc