HijriDate constructor
Creates a date from a Hijri year, month, and day on IranianHijri.official.
Throws ArgumentError when month is outside 1 to 12, day is
outside the length of that month (29 or 30), or the date is outside
HijriDate.min to HijriDate.max.
Implementation
factory HijriDate(int year, int month, int day) =>
IranianHijri.official.date(year, month, day);