pgw: Introduce test TC_s2b_createSession_v4_apco

Make sure APCO IE is properly handled and answered back.

Change-Id: Ib01fe0512866924a5afc4d6719ceacb0b4b54df2
diff --git a/library/GTPv2_Templates.ttcn b/library/GTPv2_Templates.ttcn
index c842230..a86145d 100644
--- a/library/GTPv2_Templates.ttcn
+++ b/library/GTPv2_Templates.ttcn
@@ -902,7 +902,8 @@
 			  template (omit) FullyQualifiedTEID_List teid_list,
 			  template (value) OCT2 chg_car, template (value) uint4_t bearer_id,
 			  template (omit) UserLocationInfo uli := omit,
-			  template (value) Bearer_QoS qos := ts_GTP2C_BearerQos('09'O, 0,0,0,0)) :=
+			  template (value) Bearer_QoS qos := ts_GTP2C_BearerQos('09'O, 0,0,0,0),
+			  template (omit) APCO apco := omit) :=
 ts_PDU_GTP2C('00000000'O, '000000'O, '20'O, {
 	createSessionRequest := {
 		iMSI := ts_GTP2C_Imsi(imsi),
@@ -948,7 +949,7 @@
 		signallingPriorityIndication := omit,
 		iP_Addr := omit,
 		portNumber := omit,
-		aPCO := omit,
+		aPCO := apco,
 		trustedWLANAccessNetworkIdentifier := omit,
 		cNOperatorSelectionEntity := omit,
 		presenceReportingAreaInformation := omit,
@@ -1061,7 +1062,8 @@
 			   template FullyQualifiedTEID_List fteids := *,
 			   template PDN_AddressAllocation addr := *,
 			   template APN_Restriction apn_restriction := *,
-			   template BearerContextGrouped_List bctxg := *) :=
+			   template BearerContextGrouped_List bctxg := *,
+			   template APCO exp_apco := *) :=
 tr_PDU_GTP2C(d_teid, seq, {
 	createSessionResponse := {
 		cause := tr_GTP2C_Cause(cause),
@@ -1081,7 +1083,7 @@
 		csid := *,
 		lDN := *,
 		pGW_Back_OffTime := *,
-		aPCO := *,
+		aPCO := exp_apco,
 		trustedWLANIPv4Parameters := *,
 		indicationFlags := *,
 		presenceReportingAreaAction := *,