5gc: Implement AKA authentication

deps/nas.git already has some Auth related functionaltities to calculate
XRES*, but I couldn't get them to generate proper output. Furthermore,
using them directly would include a lot of churn we don't want:
* ttcn: Otherwise ttcn/Lib_NG_NAS/LIB_NG_NAS_Functions.ttcn brings in
  tons of dependencies about Emulation stuff which is not interesting
  for us.
* .cc: We want to implement our own low level functions using our
  eclipse Titan API, as well as our own C lib dependencies (because some
  code for those dependencies is not really available in the repo).

Hence, instead use our own milenage.c implementation imported from
libosmocore (actually from a slightly modified self-contained copy we
already ported to some development branch of asterisk VoLTE project).

With this patch it is already possible to detect SQN Out-of-sync and
answer with an Auth Failure, then get a new Auth Req from network and
properly answer with an Auth Resp which the network likes and hence
answers with a Security Mode Command.

Change-Id: I11527f47e4310863124f3f02148e3f71da7d911e
---
M 5gc/C5G_Tests.cfg
M 5gc/C5G_Tests.ttcn
A 5gc/NG_CryptoFunctionDefs.cc
A 5gc/NG_CryptoFunctions.ttcn
A 5gc/key_derivation.c
A 5gc/key_derivation.h
A 5gc/milenage.c
A 5gc/milenage.h
M 5gc/regen_makefile.sh
M deps/Makefile
M library/General_Types.ttcn
M library/NG_NAS_Osmo_Templates.ttcn
12 files changed, 789 insertions(+), 17 deletions(-)