DIAMETER: Split Gy and Gx messages to their own TS files

Those interfaces reuse messages from other Diameter RFCs, but changing
the contents of the messages, eg some Mandatory fields like
Service-Context-Id which are mandatory in RFC5006, doesn't even appear
in Gx CCR in TS 29.212.

Keeping them well separated helps in avoiding confusion on users fo the
messages.

Change-Id: Ibe0d5f263813d5083e020c942283f214983162b4
diff --git a/ggsn_tests/GGSN_Tests.ttcn b/ggsn_tests/GGSN_Tests.ttcn
index a1aab9b..d7de443 100644
--- a/ggsn_tests/GGSN_Tests.ttcn
+++ b/ggsn_tests/GGSN_Tests.ttcn
@@ -34,7 +34,9 @@
 
 	import from DIAMETER_Types all;
 	import from DIAMETER_Templates all;
+	import from DIAMETER_ts29_212_Templates all;
 	import from DIAMETER_ts29_272_Templates all;
+	import from DIAMETER_ts32_299_Templates all;
 	import from DIAMETER_Emulation all;
 
 	const integer GTP0_PORT := 3386;