Switch from {future.apply} to {furrr} where possible

[kelly-sovacool]

We often use future.apply::future_lapply to create a list and then dplyr::bind_rows() to create a data frame from the elements. It would be more straight-forward to use furrr::future_map_dfr() instead.

[kelly-sovacool]

Then we could remove future.apply from Suggests if we are able to switch entirely to furrr.