Add method to convert from dynamic list to unit8 list

Author: AhmedHanafy725

packages/tfchain_client/lib/src/utils.dart

@@ -1,4 +1,12 @@
+import 'dart:typed_data';
+
 bool isValidSeed(String seed) {
   final RegExp hexRegex = RegExp(r'^[0-9a-fA-F]+$');
   return hexRegex.hasMatch(seed);
 }
+
+Uint8List dynamicListToUint8List(dynamicList) {
+  List<int> intList = dynamicList.cast<int>().toList();
+  Uint8List data = Uint8List.fromList(intList);
+  return data;
+}