feat: Add baseline models for time series

[Gerhardsa0]

Is your feature request related to a problem?

When working with time series, statistical models give a good baseline for prediction. So, a user can compare his neural network with a statistical model easily.

Desired solution

There should be global functions, which create instances of a baseline model, so the user can use them in the common Model behavior.

Possible alternatives (optional)

No response

Screenshots (optional)

No response

Additional Context (optional)

No response

[lars-reimann]

if they should have an own class

No, the baseline models are instances of the classes you define. Instead, provide global functions to create the baseline model.