Fix visuals in examples

[AVHopp]

This PR fixes all of the visual issues that we currently have in the examples. This includes

• Fixing deprecated mechanisms that were still being used
• Changing the format of of __str__ representations to avoid messing up when converting to notebook
• Adding several missing __str__ representations
• Adding an indent function for indentation within __str__ representations.

To verify, just build the documentation locally and go through the examples.

[Scienfitz]

@AVHopp are any of the doc/example pages still showing the caching? Because something that I wanted to suggest to being added is to run all of the docs/example building with caching turned off so the output doesnt disturb the pages

see https://emdgroup.github.io/baybe/userguide/envvars.html#disk-caching

[AdrianSosic]

Hi @AVHopp, here a few comments/questions.

[Scienfitz]

@AVHopp I notice this one is still open on almost the same topic #195 When do we plan to stop collecting and start fixing those?