formatTimestampEpoch method
Interprets the string as an epoch timestamp (milliseconds)
and formats it according to targetFormat.
Implementation
String? formatTimestampEpoch({String targetFormat = 'dd MM yyyy'}) {
if (this == null || this!.isEmpty) return null;
final epoch = toInt();
if (epoch == null) return null;
final dateTime = DateTime.fromMillisecondsSinceEpoch(epoch);
return dateTime.formatDate(targetFormat: targetFormat);
}