Tweaks to `predict` method of `ModelBuilder`

[drbenvincent]

Remove point_estimate kwarg of the ModelBuilder.predict method. Instead have two distinct methods...

• predict (which returns the full idata) and
• predict_point which returns the point estimate.

Tagging @michaelosthege, @twiecki.

[twiecki]

CC @shashank

[drbenvincent]

Maybe even an additional predict_proba to fit in with sktime API https://www.sktime.org/en/stable/examples/01_forecasting.html?highlight=predict_proba#predict_proba---distribution-predictions

[twiecki]

@drbenvincent yeah, I think that's a good idea.

[5hv5hvnk]

Sorry for late response, I can probably remove the point estimate from the ModelBuilder and raise a PR of the same today itself.