Functionality to retrain or continue training models using the library.

[AkshayNovacene]

I went through a couple of older issues that talk about this, but I think it is high time we have the functionality to enable the users to retrain models on the best performing model? I love this library and it offers so many functionalities except this one. I'd be glad if we could have this feature as well.

[yaniv92648]

Alternatively, providing the best performing pipeline/model & hyperparameters via a property or a method of AutoML would be nice as well