Test and possibly fix ID Request after Auth failure
In vlr_auth_fsm, we have an illegal transition from WAIT_RESP_RESYNC to
WAIT_ID_IMSI. That looks weird, to go from an UMTS AKA auth resync attempt back
to the ID Request. But looking at TS 29.002 in "Figure 25.5/2 (sheet 2 of 2):
Macro Authenticate_VLR" I see there is a branch that wants to ensure the TMSI
used in auth matches the IMSI. So if the TMSI didn't belong to the IMSI
reported back from an ID Response, we should retry auth. However, if the IMSI
reported back indeed was the one we expected, we should fail right away; it
doesn't look like we do that yet.
Write tests and fix if errors become obvious.