text into parts that fit limit: a max length in UTF-16 code units, or
SplitTextOptions with maxLength, maxBytes (UTF-8) and the markup format.
Cuts land on natural boundaries (paragraph, line, sentence, word), never inside a
grapheme or a markup entity; a fenced block, inline code, emphasis run or HTML element
longer than the limit is closed and reopened across parts. Whitespace at a cut is
dropped (the indentation of the next line is kept); whitespace-only parts are dropped.
Run time is linear in the length of text (its markup is scanned once).
Parameters
Returns
string[]