Decide what to do for `\b` and `\B` about es-regexp-unicode-character-class-escapes HOT 2 CLOSED

For compatibility with other Unicode regex engines, I think \b and \B should probably operate on simple word boundaries. What's most important though is that \b should operate on the same level as \w, so if \w matches a Unicode word character then \b should match on the boundary of a word consisting of Unicode word characters, but if \w only matches an ASCII word character then \b should also match on the boundary of a word consisting of ASCII word characters. Default word boundaries could then be implemented as \b{w} and \B{w} as well as extended grapheme cluster boundaries with \b{g}, sentence boundaries with \b{s}, etc.

Details on the \b{…} syntax:
http://unicode.org/reports/tr18/#Default_Grapheme_Clusters

from es-regexp-unicode-character-class-escapes.

This is not gonna happen as per https://esdiscuss.org/topic/questions-regarding-es6-unicode-regular-expressions#content-5. Closing the issue.

from es-regexp-unicode-character-class-escapes.