Use osmocom.construct.{Bytes,GreedyBytes} for hexstring input support

The upstream construct.{Bytes,GreedyBytes} only support bytes/bytearray
input data for the encoder, while the [newly-created]
osmocom.construct.{Bytes,GreedyBytes} support alternatively hex-string input.

This is important in the context of encoding construct-based types from
JSON, where our osmocom.utils.JsonEncoder will automatically convert any
bytes to hex-string, while re-encoding those hex-strings will fail prior
to this patch.

Change-Id: I1c8df6350c68aa408ec96ff6cd1e405ceb1a4fbb
Closes: OS#6774

pySim/apdu/__init__.py

@@ -29,7 +29,7 @@ import abc
 import typing
 from typing import List, Dict, Optional
 from termcolor import colored
-from construct import Byte, GreedyBytes
+from construct import Byte
 from construct import Optional as COptional
 from osmocom.construct import *
 from osmocom.utils import *