KFold for SVC in 0.3.0 about smartcore HOT 1 OPEN

Hi, thanks for using smartcore and finding this.

It looks like at the moment cross_validate works only for types that implement SupervisedEstimator trait; SVC implement SupervisedEstimatorBorrow instead, that is a variant that allows saving memory allocation. The solution can be:

1. or we implement SupervisedEstimator for SVC in place of SupervisedEstimatorBorrow
2. or we change cross_validate to accept SupervisedEstimatorBorrow and implement it for the other models (linear regression, ...); this way SupervisedEstimator will be used only with cross_val_predict (because it actually need a predict method).
3. or we develop a cross_validate_borrow function that takes types that implement SupervisedEstimatorBorrow

SVC was not meant to be used with cross_validate in the first place as we didn't have a use case for that. At the moment cross_validate works only with estimators that have also Predictor trait (SupervisedEstimator is composed with Predictor while the "borrow" version is not). There is note about this in the documentation but I admit it should be referenced in the cross_validate documentation.

If you have any idea about how to fix this it would be great to hear, you can also open a Pull Request to fix it. If it is indeed deemed useful and we find a solution it will be released with the next version.

NOTE: model_selection module is missing the documentation, it would be also great if you can provide it.

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