msc: add check IMEI tests

Extend BSC_ConnHdlr with new check IMEI related parameters. Add tests
for check IMEI and check IMEI early for multiple auth variations, as
well as variants where the HLR would respond with NOK or ERR.

Note that we can safely set "check-imei-rqd 0" in f_init(), because the
latest OsmoMSC version already suppors this VTY command.

Two tests do not always pass, sometimes the RAN connection breaks
before the test finishes (TC_lu_imsi_auth_tmsi_check_imei_err and
TC_lu_imsi_auth_tmsi_check_imei_nack). I have added them as expected
errors in the expected-results.xml.

Related: OS#2542
Change-Id: Ic34bb8dc8547cafb5a53df03884554dd4f72956d
4 files changed