bsc: Add testscase & infra to validate Osmux support BTS<->BSC

New TC_assignment_osmux_bts is added which tests Osmux used only
BTS<->BSC.
Existing TC_assignment_osmux is renamed to TC_assignment_osmux_cn,
and a new TC_assignment_osmux is added which tests using Osmux on both
sides (towards BTS and CN).

Related: SYS#5987
Change-Id: I6e82eb9d995de988b812001e1c4cf6923509de66
diff --git a/library/BSSMAP_Templates.ttcn b/library/BSSMAP_Templates.ttcn
index 633b060..26f7ed9 100644
--- a/library/BSSMAP_Templates.ttcn
+++ b/library/BSSMAP_Templates.ttcn
@@ -614,6 +614,10 @@
 	codecElements := valueof(elem)
 }
 
+template (present) BSSMAP_IE_Osmo_OsmuxCID tr_OsmuxCID(template (present) INT1 cid := ?) := {
+	elementIdentifier := 'F1'O,
+	osmuxCID := cid
+}
 template (value) BSSMAP_IE_Osmo_OsmuxCID ts_OsmuxCID(INT1 cid) := {
 	elementIdentifier := 'F1'O,
 	osmuxCID := cid