fix(r): Support map conversion to R vector

[paleolimbot]

Closes #281.

library(adbcdrivermanager)
library(nanoarrow)

db <- adbc_database_init(adbcsqlite::adbcsqlite(), uri = ":memory:")
con <- adbc_connection_init(db)
stream <- adbc_connection_get_info(con, 0)

tibble::as_tibble(stream)
#> # A tibble: 1 × 2
#>   info_name info_value$string_value $bool_value $int64_value $int32_bitmask
#>       <dbl> <chr>                   <lgl>              <dbl>          <int>
#> 1         0 SQLite                  NA                    NA             NA
#> # ℹ 2 more variables: info_value$string_list <list<chr>>,
#> #   $int32_to_int32_list_map <list<df[,2]>>

^{Created on 2023-08-18 with reprex v2.0.2}

[codecov-commenter]

Codecov Report

Merging #282 (b990387) into main (ad83497) will decrease coverage by 0.05%.
Report is 1 commits behind head on main.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #282      +/-   ##
==========================================
- Coverage   87.10%   87.06%   -0.05%     
==========================================
  Files          66       63       -3     
  Lines       10226     9869     -357     
==========================================
- Hits         8907     8592     -315     
+ Misses       1319     1277      -42     

Files Changed	Coverage Δ
r/R/infer-ptype.R	100.00% <ø> (ø)

... and 3 files with indirect coverage changes

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[lidavidm]

Oh whoops, I thought I was in the ADBC repo...sorry if you were planning on holding that

[paleolimbot]

All good!