[R] Update num_rows methods to output doubles not integers to prevent integer overflow

[asfimport]

In cases where Arrow objects are particularly large, this can result in an integer overflow when returning their size. See discussion on #11783 for more details of a possible solution.

library(arrow)
test_array1 <- Array$create(raw(2^31 - 1))
test_array2 <- Array$create(raw(1))
big_chunked <- chunked_array(test_array1, test_array2)

big_table <- Table$create(col = big_chunked)
big_table$num_rows
# NA

Reporter: Nicola Crane / @thisisnic
Assignee: Nicola Crane / @thisisnic

PRs and other links:

• GitHub Pull Request #13482

_{Note: This issue was originally created as ARROW-14989. Please see the migration documentation for further details.}

[asfimport]

Nicola Crane / @thisisnic:
Issue resolved by pull request 13482
#13482