Estimation with resample_results objects

[topepo]

When we run cal_estimate_*() on an object produced by fit_resamples(), it records the single value of .config since that object also inherits as "tune_results".

When cal_apply() is run on this object using a single set of predictions, there will be no .config column.

We should take a different approach for objects with class "resample_results" by first running collect_predictions() and then running cal_apply() on that.