If the .bib file has LF endings, multiline fields will be written using CRLF on Windows. - Should we add the line feed property to the meta data? (And write out accordingly?)

Steps:

• create a bib file with LF line endings and a multi line field (e.g., comment)
• add this file to .gitattributes with eol=lf
• add a test case
• Fix Bibdatabase writer

• Refs Improve serialization to fix #4877 jabref#5838
• This will fix https://sourceforge.net/p/jabref/feature-requests/857/
• Keywords: newline, CRLF, CR, new line