A FragmentScanOptions holds options specific to a FileFormat and a scan
operation.
FragmentScanOptions$create() takes the following arguments:
format: A string identifier of the file format. Currently supported values:
"csv"/"text", aliases for the same format.
...: Additional format-specific options
format = "text": see CsvConvertOptions. Note that options can only be
specified with the Arrow C++ library naming. Also, "block_size" from
CsvReadOptions may be given.
It returns the appropriate subclass of FragmentScanOptions
(e.g. CsvFragmentScanOptions).