Prefit for CQR

[LacombeLouis]

Is your feature request related to a problem? Please describe. No prefit method for CQR. This means that it is not possible to use a trained model.

Describe the solution you'd like Add a prefit method in the cv for the CQR method.

Describe alternatives you've considered Could create different wrappers and add them to the "authorized" methods for MAPIE, but this would prove more complex than helpful.