Use batch requests

[jennybc]

In many places I use purrr::map() when I really should send a batch request.

https://developers.google.com/drive/api/v3/batch

[gowerc]

Hey @jennybc , Was just searching to see if this functionality existed when I found this issue. Any chance I could persuade you to bump this up the priority list ? :)

We currently are wanting to upload ~200-300 files to googledrive and are hitting slowdowns as they are all going sequentially. Would be awesome if batch requests was supported for similar sorts of use cases.