findClusterBreak
fun findClusterBreak(str: String, pos: Int, forward: Boolean = true, includeExtending: Boolean = true): Int
Returns a next grapheme cluster break after (not equal to) pos, if forward is true, or before otherwise. Returns pos itself if no further cluster break is available in the string. Moves across surrogate pairs, extending characters (when includeExtending is true), characters joined with zero-width joiners, and flag emoji.