Modifications to use sphinx gallery for the tutorials.

[TeresiaOlsson]

This is an example for how to use sphinx gallery for the tutorials.

I think it looks very nice and gives both the option to download files and run them interactively with binder. It follows this: https://sphinx-gallery.github.io/stable/auto_examples/index.html

Downsides are:

• Some parts of the tutorials needs to use rst syntax instead of markdown.
• Sphinx gallery generates notebooks from python files. It can't use notebooks directly. So someone writing a tutorial need to first write the notebooks to test, then export to a py file and make some manual modifications to change markdown to rst.

However, py files are better for version control than notebooks.

It looks like this if you don't want to build locally or download the artifact from the workflow to be able to see it.