pySim-shell: Create + use per-RuntimeLchan SimCardCommands

This new approach will "fork" separate SimCardCommands instances
for each RuntimeLchan.  Higher-layer code should now always use the
RuntimeLchan.scc rather than the RuntimeState.card._scc in order to
make sure commands use the correct logical channel.

Change-Id: I13e2e871f2afc2460d9fd1cd566de42267c7d389
Related: OS#6230
diff --git a/pySim/commands.py b/pySim/commands.py
index 3edee98..336cf0c 100644
--- a/pySim/commands.py
+++ b/pySim/commands.py
@@ -74,6 +74,7 @@
         """Fork a per-lchan specific SimCardCommands instance off the current instance."""
         ret = SimCardCommands(transport = self._tp, lchan_nr = lchan_nr)
         ret.cla_byte = self._cla_byte
+        ret.sel_ctrl = self.sel_ctrl
         return ret
 
     @property