refactor: support disabling CSV quote parsing by NONE_QUOTE

[huangzengtian]

• Add NONE_QUOTE constant in CsvConstant.
• Add Javadoc to CsvReaderBuilder#quote(Character quote) for NONE_QUOTE usage

Purpose of the pull request

Closed: #846

What's changed?

Rationale
Currently, the quote configuration in CsvReaderBuilder does not support an explicit "disabled" state. Setting it to null is ambiguous (could mean "use default" or "disable"). This PR introduces a special constant to explicitly disable quote parsing, which is essential for processing raw TSV/CSV data (like Amazon reports) where quotes are part of the literal content and should not be escaped or wrapped.

Design Decisions
Introduced CsvConstant.NONE_QUOTE ('\0'): Followed the industrial practice of Apache Commons CSV (where withQuote(null) disables quoting).

Enhanced Javadoc: Added clear instructions in CsvReaderBuilder#quote to guide users on how to use NONE_QUOTE.

Checklist

• [✓] I have read the Contributor Guide.
• [✓] I have written the necessary doc or comment.
• [✓] I have added the necessary unit tests and all cases have passed.

[delei]

LGTM