enable setting stop_iter with brulee mlp()

[simonpcouch]

Closes #1050.🏄

stop_iter had been mistakenly registered as a model argument for mlp().

library(tidymodels)

set.seed(1)
mlp(hidden_units = 5, epochs = 100) %>% 
  set_engine("brulee", stop_iter = 5)  %>% 
  set_mode("regression") %>%
  fit(price ~ latitude + longitude, data = Sacramento)
#> parsnip model object
#> 
#> Multilayer perceptron
#> 
#> relu activation
#> 5 hidden units,  21 model parameters
#> 932 samples, 2 features, numeric outcome 
#> weight decay: 0.001 
#> dropout proportion: 0 
#> batch size: 839 
#> learn rate: 0.01 
#> scaled validation loss after 100 epochs: 1.29


# tunable information is still preserved:
set.seed(1)
res <- 
  tune_grid(
    mlp(hidden_units = 3, epochs = 50) %>% 
      set_engine("brulee", stop_iter = tune())  %>% 
      set_mode("regression"),
    price ~ latitude + longitude,
    vfold_cv(Sacramento, v = 5),
    grid = 3
  )
#> → A | warning: A correlation computation is required, but `estimate` is constant and has 0
#>                standard deviation, resulting in a divide by 0 error. `NA` will be returned.
#> There were issues with some computations   A: x1
#> There were issues with some computations   A: x4
#> There were issues with some computations   A: x5
#> 

collect_metrics(res)
#> # A tibble: 6 × 7
#>   stop_iter .metric .estimator    mean     n  std_err .config             
#>       <int> <chr>   <chr>        <dbl> <int>    <dbl> <chr>               
#> 1        19 rmse    standard   1.46e+5     5  1.17e+4 Preprocessor1_Model1
#> 2        19 rsq     standard   2.61e-2     1 NA       Preprocessor1_Model1
#> 3        13 rmse    standard   2.74e+9     5  2.74e+9 Preprocessor1_Model2
#> 4        13 rsq     standard   8.45e-2     1 NA       Preprocessor1_Model2
#> 5         5 rmse    standard   2.99e+9     5  1.88e+9 Preprocessor1_Model3
#> 6         5 rsq     standard   1.14e-1     2  2.74e-2 Preprocessor1_Model3

^{Created on 2024-01-16 with reprex v2.0.2}

Probably worth writing up a quick check to see if we've done this anywhere else. :)

[topepo]

Looks great!

[github-actions]

This pull request has been automatically locked. If you believe you have found a related problem, please file a new issue (with a reprex: https://reprex.tidyverse.org) and link to this issue.