Export a wrapper around purrr map() to workers rather than map() itself

[DavisVaughan]

To avoid cases where we ship map() from purrr 1.0.0 to the workers, but the workers have purrr < 1.0.0, resulting in an error like:

Error in map_("list", .x, .f, ..., .progress = .progress) : 
  could not find function "map_"

Something like:

# rather than this
...furrr_map <- purrr::map

# do this
...furrr_map <- function(...) {
  purrr::map(...)
}

https://stackoverflow.com/questions/75660223/r-furure-map-across-multiple-servers