PCU: also test GSGN originated PS/CS Paging containing TMSI

This additional couple of test cases reveals several bugs:

  1) the IUT encodes a erroneous RR Paging Request message
     containing P-TMSI, so TITAN fails to decode it;

  2) the IUT prints an invalid P-TMSI in its log output
     due to load of misaligned address (found by UBSan).

[1] I97fd5ffc15a4a58112d7c37c69b7ac42b0741a0e
[2] Icf8836f216793e342b239c8e6645aac1e82bf324

Change-Id: I7fbec5b2c5c3943a7413417b623f55c135c152d7
diff --git a/library/Osmocom_Gb_Types.ttcn b/library/Osmocom_Gb_Types.ttcn
index 518ca80..9189b3e 100644
--- a/library/Osmocom_Gb_Types.ttcn
+++ b/library/Osmocom_Gb_Types.ttcn
@@ -1333,6 +1333,22 @@
 		}
 	}
 
+	template PDU_BSSGP ts_BSSGP_CS_PAGING_PTMSI(BssgpBvci bvci, hexstring imsi, GsmTmsi tmsi) := {
+		pDU_BSSGP_PAGING_CS := {
+			bssgpPduType := '07'O,
+			iMSI := ts_BSSGP_IMSI(imsi),
+			dRX_Parameters := t_defaultDRXparam,
+			paging_Field4 := {
+				bVCI := t_BSSGP_BVCI(bvci)
+			},
+			tLLI := omit,
+			channel_needed := omit,
+			eMLPP_Priority := omit,
+			tMSI := ts_BSSGP_TMSI(tmsi),
+			global_CN_Id := omit
+		}
+	}
+
 	template PDU_BSSGP tr_BSSGP_PS_PAGING(BssgpBvci bvci) := {
 		pDU_BSSGP_PAGING_PS := {
 			bssgpPduType := '06'O,