Problems with caret sbf objects

**Minimal dataset**

```
library(caret)
library(iml)
dat <- twoClassSim(100)
X <- dat[,1:5]
X$y <- dat[["Class"]]
```

**Minimal, runnable code**

```
tr <- sbf(
y ~ .,
data = X,
sbfControl = sbfControl(
functions = caretSBF,
verbose = FALSE,
method = "cv",
number = 10
),
trControl = trainControl(classProbs = TRUE),
method = "svmLinear"
)
```

**Problems start**

```
Predictor$new(tr, X, y = "y")
```
> Prediction task:unknown

```
pred <- Predictor$new(tr, X, y = "y")
Shapley$new(pred, X, X[1, ])
```
> Error in colMeans(self$predictor$predict(private$sampler$get.x()):
x must be numeric

These problems don't happen if I create `Predictor` with a `fit` object extracted from `dbf` (`Predictor$new(tr$fit, ...`) but [this is a bad idea](https://github.com/topepo/caret/issues/1182#issuecomment-776231373).

Thanks for making `iml`. Your book is amazing :grin:

**Session info**

```

R version 4.0.2 (2020-06-22)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS 10.16

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib

locale:
[1] en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] iml_0.10.1 caret_6.0-86 ggplot2_3.3.2 lattice_0.20-41

loaded via a namespace (and not attached):
[1] Metrics_0.1.4 statmod_1.4.35 tidyselect_1.1.0
[4] kernlab_0.9-29 listenv_0.8.0 purrr_0.3.4
[7] reshape2_1.4.4 splines_4.0.2 colorspace_1.4-1
[10] vctrs_0.3.4 generics_0.1.0 stats4_4.0.2
[13] survival_3.2-7 prodlim_2019.11.13 rlang_0.4.8
[16] e1071_1.7-4 ModelMetrics_1.2.2.2 nloptr_1.2.2.2
[19] pillar_1.4.6 glue_1.4.2 withr_2.3.0
[22] foreach_1.5.1 lifecycle_0.2.0 plyr_1.8.6
[25] lava_1.6.8 stringr_1.4.0 timeDate_3043.102
[28] munsell_0.5.0 gtable_0.3.0 prediction_0.3.14
[31] future_1.20.1 recipes_0.1.14 codetools_0.2-16
[34] parallel_4.0.2 class_7.3-17 Rcpp_1.0.5
[37] backports_1.1.10 checkmate_2.0.0 scales_1.1.1
[40] ipred_0.9-9 parallelly_1.21.0 lme4_1.1-25
[43] digest_0.6.27 stringi_1.5.3 dplyr_1.0.2
[46] grid_4.0.2 tools_4.0.2 magrittr_1.5
[49] tibble_3.0.4 crayon_1.3.4 tidyr_1.1.2
[52] pkgconfig_2.0.3 MASS_7.3-53 ellipsis_0.3.1
[55] Matrix_1.2-18 data.table_1.13.2 pROC_1.16.2
[58] lubridate_1.7.9 gower_0.2.2 minqa_1.2.4
[61] rstudioapi_0.11 iterators_1.0.13 globals_0.13.1
[64] R6_2.5.0 boot_1.3-25 rpart_4.1-15
[67] nnet_7.3-14 nlme_3.1-150 compiler_4.0.2
```