solaraviz kwargs related bugfix

[quaquel]

If MyModel .__init__() uses **kwargs to allow additional optional model configuration this errors because of the parameter check introduced in #2454. This PR addresses this by excluding kwargs explicitly in _check_model_params.

In passing, it also removes a user warning related to the conditional use of hooks introduced in #2460.

This closes #2462.

[quaquel]

Thinking about this a bit more, I am wondering whether we should not also change

    for name in model_params:
        if name not in model_parameters:
            raise ValueError(f"Invalid model parameter: {name}")

to

    for name in model_params:
        if (name not in model_parameters
           and "kwargs" not in model_parameters
        ):
            raise ValueError(f"Invalid model parameter: {name}")

That is, if you have a user settable parameter in model_params but are using **kwargs in the signature, the user settable parameter will work fine.

[Corvince]

Nice quick fix and agree with your comment - when kwargs are used we should not raise an Error.

Would be good to also add both cases to the unit tests