Migrate over to using pyosmocom

We're creating a 'pyosmocom' pypi module which contains a number of core
Osmocom libraries / interfaces that are not specific to SIM card stuff
contained here.

The main modules moved in this initial step are pySim.tlv, pySim.utils
and pySim.construct. utils is split, not all of the contents is
unrelated to SIM Cards.  The other two are moved completely.

Change-Id: I4b63e45bcb0c9ba2424dacf85e0222aee735f411

contrib/unber.py

@@ -6,7 +6,8 @@
 import sys
 import argparse
 
-from pySim.utils import bertlv_parse_one, bertlv_encode_tag, b2h, h2b
+from osmocom.utils import b2h, h2b
+from osmocom.tlv import bertlv_parse_one, bertlv_encode_tag
 
 def process_one_level(content: bytes, indent: int):
     remainder = content