ARROW-11832: [R] Handle conversion of extra nested struct column

[romainfrancois]

library(arrow, warn.conflicts = FALSE)

df <- structure(list(col = structure(list(structure(list(list(structure(1))), class = "inner")), class = "outer")), class = "data.frame", row.names = c(NA, -1L))
Array$create(df)
#> StructArray
#> <struct<col: list<item: list<item: list<item: double>>>>>
#> -- is_valid: all not null
#> -- child 0 type: list<item: list<item: list<item: double>>>
#>   [
#>     [
#>       [
#>         [
#>           1
#>         ]
#>       ]
#>     ]
#>   ]

^{Created on 2021-04-07 by the reprex package (v0.3.0)}

[github-actions]

https://issues.apache.org/jira/browse/ARROW-11832

[romainfrancois]

following up @jonkeane finding from #8650

[jonkeane]

This looks good to me. I've tested it out on the simple features objects we were benchmarking with where I discovered this first, and those work fine now from parquet -> arrow -> R and then critically R -> arrow (and then -> feather/parquet) without needing to have the {sf} package loaded.

It also looks like we were able to get rid of a TODO on the way, nice!

That RTools 35 failure is unrelated to this.