Converts a comma-separated values (CSV) string to a 2D array.

Use Array.prototype.slice() and Array.prototype.indexOf('\n') to remove the first row (title row) if omitFirstRow is true. Use String.prototype.split('\n') to create a string for each row, then String.prototype.split(delimiter) to separate the values in each row. Omit the second argument, delimiter, to use a default delimiter of ,. Omit the third argument, omitFirstRow, to include the first row (title row) of the CSV string.