Examples in documentation for standard library

[lars-reimann]

1. Translate the Python examples of the library into Safe-DS and include them after an @examples tag in the documentation comments.
2. Update the markdown generator to include the examples (wrapped in a code block).
3. Add tests to ensure that the examples contain neither errors nor warnings.

TODO:

Add examples for

• [x] data.tabular.transformation
• [x] ml.classical.classificiation
• [x] ml.classical.regression
• [ ] data.image
• [ ] data.tabular.containers.TaggedTable
• [ ] data.tabular.containers.TimeSeries
• [ ] data.tabular.typing
• [ ] ml.nn

[lars-reimann]

This is also particularly helpful for lang classes like List or Map, which can only be created by literals.