revamp parsnip model list for censored

[topepo]

The model mode is broken into "regression", "classification" and essentially "both". We should probably change the nature of this column to accommodate the censored package.

[juliasilge]

Do you mean the table at https://www.tidymodels.org/find/parsnip/?

[hfrick]

@juliasilge yes, that is what we talked about. I said it'd be handy to be able to find a list of all available model/engine combinations for say classification. Currently you could get that by filtering for "classification" and "both" but when adding the censored regression mode that gets fairly messy.