[css-counter-styles] Define extended CJK longhand counter styles range (#12383)

* restore old spec

* add implementation tier clarification

* extend Korean range to embrace negative

* fix linkings

* Update css-counter-styles-3/Overview.bs

Co-authored-by: fantasai <fantasai.bugs@inkedblade.net>

* simplify the exteded implimentation description

* remove optional closing tags

* use semantic line breaking

* Update css-counter-styles-3/Overview.bs

Co-authored-by: fantasai <fantasai.bugs@inkedblade.net>

* Update css-counter-styles-3/Overview.bs

* Update css-counter-styles-3/Overview.bs

* Update css-counter-styles-3/Overview.bs

Co-authored-by: fantasai <fantasai.bugs@inkedblade.net>

* Update css-counter-styles-3/Overview.bs

Co-authored-by: fantasai <fantasai.bugs@inkedblade.net>

* Update css-counter-styles-3/Overview.bs

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Co-authored-by: fantasai <fantasai.bugs@inkedblade.net>
Co-authored-by: Tab Atkins Jr. <jackalmage@gmail.com>

Author: 3 people