CSV Read/Write + DataTables.ConvertTableToPlainText: Support for alternative/custom line break symbols within cells

[jochenwezel]

Unicode already provides several line-break-symbols, e.g.

• ␤ https://www.htmlsymbols.xyz/unicode/U+2424
• https://unicode.org/reports/tr14/#Algorithm
• https://en.wikipedia.org/wiki/Newline#Unicode