[AMF] Fix N2 Handover - copy PDU session info

After N2 Handover (1 AMF, multiple gNB's) was successfully executed, the
PDU session was not properly released afterwards on PDU Session Release
Request from UE.

The reason was that after N2 Handover the new 'ran_ue' context did not
have any information about the active PDU sessions.

Copy the information about PDU sessions from old ran_ue context to the
new one.

src/amf/ngap-handler.c

@@ -3140,6 +3140,8 @@ void ngap_handle_handover_required(
     target_ue->initial_context_setup_request_sent =
             source_ue->initial_context_setup_request_sent;
 
+    target_ue->psimask.activated = source_ue->psimask.activated;
+
     ogs_debug("    Target : RAN_UE_NGAP_ID[%d] AMF_UE_NGAP_ID[%lld] ",
         target_ue->ran_ue_ngap_id, (long long)target_ue->amf_ue_ngap_id);