MSC_Tests: add testcase TC_sgsap_impl_imsi_det_noneps

We have a testcase that sends an explicit (UE-Initiated) imsi detach
from non EPS services. Lets also cover the case for an implicit
(Network-initated) detach.

Change-Id: I76049e6717680c54c18f97b7cd51944901a81ae7
Related: OS#3614
2 files changed