Introduce APDU/TPDU trace decoder

This introduces a new pySim.apdu module hierarchy, which contains
classes that represent TPDU/APDUs as exchanged between
SIM/UICC/USIM/ISIM card and UE.

It contains instruction level decoders for SELECT, READ BINARY and
friends, and then uses the pySim.filesystem.Runtime{Lchan,State} classes
to keep track of the currently selected EF/DF/ADF for each logical
channel, and uses the file-specific decoder classes of pySim to decode
the actual file content that is being read or written.

This provides a much more meaningful decode of protocol traces than
wireshark will ever be able to give us.

Furthermore, there's the new pySim.apdu_source set of classes which
provides "input plugins" for obtaining APDU traces in a variety of
formats.  So far, GSMTAP UDP live capture and pyshark based RSPRO
live and pcap file reading are imlpemented.

Change-Id: I862d93163d495a294364168f7818641e47b18c0a
Closes: OS#5126

pySim/apdu_source/__init__.py

@@ -0,0 +1,35 @@
+import abc
+import logging
+from typing import Union
+from pySim.apdu import Apdu, Tpdu, CardReset, TpduFilter
+
+PacketType = Union[Apdu, Tpdu, CardReset]
+
+logger = logging.getLogger(__name__)
+
+class ApduSource(abc.ABC):
+    def __init__(self):
+        self.apdu_filter = TpduFilter(None)
+
+    @abc.abstractmethod
+    def read_packet(self) -> PacketType:
+        """Read one packet from the source."""
+        pass
+
+    def read(self) -> Union[Apdu, CardReset]:
+        """Main function to call by the user: Blocking read, returns Apdu or CardReset."""
+        apdu = None
+        # loop until we actually have an APDU to return
+        while not apdu:
+            r = self.read_packet()
+            if not r:
+                continue
+            if isinstance(r, Tpdu):
+                apdu = self.apdu_filter.input_tpdu(r)
+            elif isinstance(r, Apdu):
+                apdu = r
+            elif isinstance(r, CardReset):
+                apdu = r
+            else:
+                ValueError('Unknown read_packet() return %s' % r)
+        return apdu