Support line breaking rules in East Asian languages

[sttk]

At the moment, the line breaking rule only supports end-of-line and punctuation marks tentative English and Japanese rules. This is not sufficient and also not accurate. I'll support line breaking rules specified in UAX#14, and more Japanese specific rules if necessary.

Ref.

• https://www.unicode.org/reports/tr14/
• https://en.wikipedia.org/wiki/Line_breaking_rules_in_East_Asian_languages

[sttk]

UAX14 Implementations in other projects:

• https://github.com/rivo/uniseg/blob/master/linerules.go
• https://pkg.go.dev/github.com/npillmayer/uax@v0.2.0/uax14#LineWrap
• https://github.com/gorilla/i18n/blob/main/linebreak/linebreak.go