Add narrow no-break space (NNBSP, U+202F)

[ryan-carpenter]

Encode-Sans already includes THIN SPACE (U+2009) and NO-BREAK SPACE (NBSP; U+00A0), but does not include a narrow no-break space (U+202F), which could have the same width as a thin space. As a technical writer, I use NNBSP frequently to conserve space in tabular data. NNBSP is also important for some languages (e.g., French).

• Unicode character information: https://unicode.org/cldr/utility/character.jsp?a=202F
• Other fonts that support NNBSP: https://www.fileformat.info/info/unicode/char/202f/fontsupport.htm
• Potential complications associated with NNBSP: https://wiki.openoffice.org/wiki/Talk:Non_Breaking_Spaces_Before_Punctuation_In_French_(espaces_ins%C3%A9cables)
• Proposal to establish NNBSP as a definitavely usable avatar of THIN SPACE: https://www.unicode.org/L2/L2019/19169-nnbsp-thin-space.pdf