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GH-33526: [R] Implement new function open_dataset_csv with signature more closely matching read_csv_arrow (#33614)

This PR implements a wrapper around `open_dataset()` specifically for value-delimited files. It takes the parameters from `open_dataset()` and appends the parameters of `read_csv_arrow()` which are compatible with `open_dataset()`. This should make it easier for users to switch between the two, e.g.:

``` r
library(arrow)
library(dplyr)

# Set up directory for examples
tf <- tempfile()
dir.create(tf)
on.exit(unlink(tf))
df <- data.frame(x = c("1", "2", "NULL"))

file_path <- file.path(tf, "file1.txt")
write.table(df, file_path, sep = ",", row.names = FALSE)

read_csv_arrow(file_path, na = c("", "NA", "NULL"), col_names = "y", skip = 1)
#> # A tibble: 3 × 1
#>       y
#>   <int>
#> 1     1
#> 2     2
#> 3    NA

open_csv_dataset(file_path, na = c("", "NA", "NULL"), col_names = "y", skip = 1) %>% collect()
#> # A tibble: 3 × 1
#>       y
#>   <int>
#> 1     1
#> 2     2
#> 3    NA
```

This PR also hooks up the "na" (readr-style) parameter to "null_values" (i.e. CSVConvertOptions parameter).

In the process of making this PR, I also refactored `CsvFileFormat$create()`.  Unfortunately, many changes needed to be made at once, which has considerably increasing the size/complexity of this PR.

Authored-by: Nic Crane <thisisnic@gmail.com>
Signed-off-by: Nic Crane <thisisnic@gmail.com>