Remove imitation learning from MPInterface

[ottofabian]

Is your feature request related to a problem? Please describe.
Learning the MP parameters with imitation learning (IL) is a really specific setting and should not be part of a general MP interface., especially not as a mandatory method to implement for each subclass.
Learning should be part of someone's library using this library.
At the very best, this setting should be included as demo or example how to use the library.

Describe the solution you'd like
Remove the learning from the general interface completely. If it is absolutely necessary, I would only add it as an example how to use the MPs in an IL setting

Describe alternatives you've considered
n.a.

Additional context
n.a.