Convert an 'orsf_summary' object into a data.table
object.
Examples
if (FALSE) { # \dontrun{
library(data.table)
object <- orsf(pbc_orsf, Surv(time, status) ~ . - id, n_tree = 25)
smry <- orsf_summarize_uni(object, n_variables = 2)
as.data.table(smry)
} # }