Allow workflows without recipes

[topepo]

If we have a formula method,predict_boots() fails

library(tidymodels)
library(workboots)

car_pred_int <-
  workflow(mpg ~ ., linear_reg()) %>%
  predict_boots(
    n = 2000,
    training_data = mtcars[3:32,],
    new_data = mtcars[1:2,]
  )
#> Error in UseMethod("filter"): no applicable method for 'filter' applied to an object of class "NULL"

^{Created on 2024-01-12 with reprex v2.0.2}

I assume that this isn’t intentional.

I think that this happens when you are trying to get the names of the predictor columns. I think have some APIs for that (I don't think that they are in any packages yet) if you want some help.

Are there any other “missing pieces” in terms of APIs that you needed but either don’t exist or are hard to find?