introduce a TTCN3 test suite for SCCP

This test suite acts as an SCCP server on top of M3UA.

SCCP tests are run against the sccp_demo_user program which
can be found in libosmo-sccp/examples. This program must be
started in client mode: sccp_demo_user -c
The SCCP test suite should then work out of the box with
the provided SCCP_Tests.cfg file and this additional change
to sccp_demo_user default point codes:
https://gerrit.osmocom.org/#/c/libosmo-sccp/+/9652/

There is currently only one test, for the libosmo-sccp crash
reported as issue OS#2666. The implementation of this test
is currently using an ugly workaround due to shortcomings of
the M3UA Emulation layer (see source code comments). Whether
a better solution is feasible is still to be determined.

The test requires a patch to the SCCP Protocol Emulation which
has been submitted upstream: https://git.eclipse.org/r/#/c/124552/

Change-Id: I03f5e8b282a7396b45417495c88d8fb81b26cda8
Related: OS#2666
diff --git a/sccp/SCCP_Tests.default b/sccp/SCCP_Tests.default
new file mode 100644
index 0000000..7d16e5b
--- /dev/null
+++ b/sccp/SCCP_Tests.default
@@ -0,0 +1,41 @@
+[LOGGING]
+FileMask := LOG_ALL | TTCN_MATCHING | DEBUG_ENCDEC;
+
+BSSAP.FileMask := LOG_NOTHING;
+"SCCP_Test_M3UA".FileMask := ERROR | WARNING;
+"SCCP_Test_SCCP".FileMask := ERROR | WARNING;
+"IPA-CTRL-IPA".FileMask := ERROR | WARNING;
+mtc.FileMask := ERROR | WARNING;
+
+[TESTPORT_PARAMETERS]
+*.SCCP_DEMO_USER_VTY.CTRL_MODE := "client"
+*.SCCP_DEMO_USER_VTY.CTRL_HOSTNAME := "127.0.0.1"
+*.SCCP_DEMO_USER_VTY.CTRL_PORTNUM := "2325"
+*.SCCP_DEMO_USER_VTY.CTRL_LOGIN_SKIPPED := "yes"
+*.SCCP_DEMO_USER_VTY.CTRL_DETECT_SERVER_DISCONNECTED := "yes"
+*.SCCP_DEMO_USER_VTY.CTRL_READMODE := "buffered"
+*.SCCP_DEMO_USER_VTY.CTRL_CLIENT_CLEANUP_LINEFEED := "yes"
+*.SCCP_DEMO_USER_VTY.PROMPT1 := "sccp-demo-user> "
+
+[MODULE_PARAMETERS]
+M3UA_Emulation.tsp_logVerbose := true;
+M3UA_Emulation.tsp_SCTP_Server_Mode := true;
+M3UA_Emulation.tsp_M3UA_Server_Mode := true;
+SCCP_Tests.sccp_cfg := {
+	{
+			sccp_service_type := "mtp3_itu",
+			sctp_addr := { 2905, "127.0.0.1", 2905, "127.0.0.2" },
+			own_pc := 185,
+			own_ssn := 254,
+			peer_pc := 23,
+			peer_ssn := 254,
+			sio := '83'O,
+			rctx := 0
+	}
+};
+
+Osmocom_VTY_Functions.mp_prompt_prefix := "sccp-demo-user";
+
+[MAIN_CONTROLLER]
+
+[EXECUTE]