function isQuoted(val) {
        return (
          (val.charAt(0) === '"' && val.slice(-1) === '"') ||
          (val.charAt(0) === "'" && val.slice(-1) === "'")
        )
      }
Matching function shared among the 2022 detectors JP, CN and KR
Counts up the number of legal an unrecognized escape sequences in
the sample of text, and computes a score based on the total number &
the proportion that fit the encoding.


@param text the byte buffer containing text to analyse
@param textLen  the size of the text in the byte.
@param escapeSequences the byte escape sequences to test for.
@return match quality, in the range of 0-100.