[R] fix max_rows_per_group must be a positive number

[r2evans]

Describe the bug, including details regarding any error messages, version, and platform.

arrow::write_dataset(dataset = x, path = "...", partitioning = somekeys,
                         max_rows_per_file = 0L)
# Error: Invalid: max_rows_per_group must be a positive number

The document says

max_rows_per_file: maximum number of rows per file. If greater than 0
          then this will limit how many rows are placed in any single
          file. Default is 0L.

min_rows_per_group: write the row groups to the disk when this number
          of rows have accumulated. Default is 0L.

Two things:

• the error references an argument that was not provided
• either update the documentation or accept 0 as an acceptable argument (that just reasserts the behavior of "no limit")

Component(s)

R

[thisisnic]

Thanks for reporting this @r2evans, can confirm I can reproduce this. The error is being propagated from the C++ layer, and I think it might be related to #39995, but need to double-check.