testing of models/transformers toolkit

[LionelMassoulard]

Leverage existing tests within aikit to offer a toolbox to check behavior of new klass. The toolkit would :

• test what data structured is accepted and not (DataFrame, numpy, sparse, ...)
• test respect of sklearn contrats (fit return self, get_params, ...)
• test output shape
• test if mono or multi-output are accepted
• ...