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/global_platform/http.py

@@ -17,9 +17,10 @@ Also known as SCP81 for SIM/USIM/UICC/eUICC/eSIM OTA.
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-from construct import Struct, Int8ub, Int16ub, Bytes, GreedyBytes, GreedyString, BytesInteger
+from construct import Struct, Int8ub, Int16ub, GreedyString, BytesInteger
 from construct import this, len_, Rebuild, Const
 from construct import Optional as COptional
+from osmocom.construct import Bytes, GreedyBytes
 from osmocom.tlv import BER_TLV_IE
 
 from pySim import cat

pySim/global_platform/scp.py

@@ -20,8 +20,9 @@ import logging
 from typing import Optional
 from Cryptodome.Cipher import DES3, DES
 from Cryptodome.Util.strxor import strxor
-from construct import Struct, Bytes, Int8ub, Int16ub, Const
+from construct import Struct, Int8ub, Int16ub, Const
 from construct import Optional as COptional
+from osmocom.construct import Bytes
 from osmocom.utils import b2h
 from osmocom.tlv import bertlv_parse_len, bertlv_encode_len
 from pySim.utils import parse_command_apdu