Extend enumeration support to non-string levels

[eddelbuettel]

This PR adds support for reads of enumeration types possible in arrow but not in the stricter R factor setup. For other types we collapse the levels information into the actual data (i.e. converting from factor to vector). One such example where the last two columns were written from arrow as dictionaries with, respectively, float64 and bool levels:

$ Rscript -e 'tiledb::tiledb_array("/some/uri/some/where", return_as="tibble")[]'
# A tibble: 5 × 5
  soma_joinid   int string `enum-float64` `enum-bool`
      <int64> <int> <chr>           <dbl> <lgl>      
1           0   100 red               1.2 TRUE       
2           1   101 yellow            3.4 TRUE       
3           2   102 green             5.6 FALSE      
4           3   103 red               1.2 TRUE       
5           4   104 green             5.6 FALSE      
$ 

SC 36358

[shortcut-integration]

This pull request has been linked to Shortcut Story #36358: Extend enumeration support.

[johnkerl]

Context: single-cell-data/TileDB-SOMA#1846