Improve date type detection in csv files

[MaximMoinat]

Detection of the date type is limited when scanning csv files. The only two formats that will be detected are yyyy.mm.dd or mm.dd.yy (the separator can be anything and the two formats can be used interchangeable in the same document). Other orders of year, month, day will not be detected as dates.

We could use DateTimeFormatter patterns as an alternative to test multiple formats.

    public boolean isValid(String dateStr) {
        foreach dateFormat:
        DateFormat sdf = new SimpleDateFormat(dateFormat);
        sdf.setLenient(false);
        try {
            sdf.parse(dateStr);
            return true;
        } catch (ParseException e) {
            return false;
        }
        return false;
    }

Link to current StringUtilities.isDate method for reference: https://github.com/OHDSI/WhiteRabbit/blob/0247306c4ed836c71d71fb1615ca6ddf90ae200d/rabbit-core/src/main/java/org/ohdsi/utilities/StringUtilities.java#L839-L873