usim/opc: Add support to write completely random OPC

Allow to set the OPC, write it out to the state, generate it randomly.

pySim/cards.py

@@ -337,9 +337,8 @@ class SysmoUSIMgr1(Card):
 		data, sw = self._scc._tp.send_apdu_checksw("0020000A083332323133323332")
 
 		# TODO: move into SimCardCommands
-		# TODO: Add OPC support support to pySIM
 		par = ( p['ki'] +			# 16b  K
-			32*"F" +			# 32b  OPC
+			p['opc'] +			# 32b  OPC
 			self._e_iccid(p['iccid']) +	# 10b  ICCID
 			self._e_imsi(p['imsi'])		#  9b  IMSI_len + id_type(9) + IMSI
 			)