[C++][Dataset] Add ConvertOptions and ReadOptions to CsvFileFormat

[asfimport]

#7033 does not add ConvertOptions (including alternate spellings for null/true/false, etc) or ReadOptions (block_size, column name customization, etc). These will be helpful but will require some discussion to find the optimal way to integrate them with dataset::

Reporter: Ben Kietzman / @bkietz
Assignee: David Li / @lidavidm

Related issues:

• [R] Better messaging for currently unsupported CSV options in open_dataset (is related to)
• [C++][Dataset] Extract format-specific scan options from FileFormat (is related to)
• [R] Accept format-specific scan options in collect() (is related to)
• [C++] Move csv::ReadOptions::skip_rows to csv::ParseOptions::skip_rows (is related to)

PRs and other links:

• GitHub Pull Request #9725

_{Note: This issue was originally created as ARROW-8631. Please see the migration documentation for further details.}

[asfimport]

David Li / @lidavidm:
Following on from ARROW-9749, we now have ConvertOptions. ReadOptions doesn't fit neatly into either the dataset-global or scan-specific buckets (skip_rows, column names are in the former; block_size is in the latter) so fields will have to be inlined (or it could be made part of CsvFileFormat with an explicit block_size field in CsvFragmentScanOptions). 

I'll also plumb through the options into Python and add a ScannerBuilder method for setting them.

[asfimport]

Ben Kietzman / @bkietz:
Issue resolved by pull request 9725
#9725