add three tests for CIPHER MODE COMPLETE without algo

Add three tests which exercise MSC behaviour when a CIPHER MODE
COMPLETE command lacks the optional chosenEncryptionAlgorithm IE.
Check for behaviour with A5/1, A5/3, and A5/1 + A5/3 configured
in the network, and expect the location update to succeed.

These tests pass on master, but they should somehow verify the
cipher the MSC ends up using. I am not quite sure how to do that.
Would inspecting the MSC's VTY be a reasonable approach? How
could his be done by code which runs on BSC_ConnectionHandler?

Change-Id: I1a2a126795c544613a7a87e238e1fc8c4e943885
Related: OS#2872
diff --git a/library/BSSMAP_Templates.ttcn b/library/BSSMAP_Templates.ttcn
index b7230cd..02c84e2 100644
--- a/library/BSSMAP_Templates.ttcn
+++ b/library/BSSMAP_Templates.ttcn
@@ -1174,6 +1174,19 @@
 	}
 }
 
+template PDU_BSSAP ts_BSSMAP_CipherModeComplAlg(template BSSMAP_IE_ChosenEncryptionAlgorithm chosenEncryptionAlgorithm := ?)
+modifies ts_BSSAP_BSSMAP := {
+	pdu := {
+		bssmap := {
+			cipherModeComplete := {
+				messageType := '55'O,
+				layer3MessageContents := omit,
+				chosenEncryptionAlgorithm := chosenEncryptionAlgorithm
+			}
+		}
+	}
+}
+
 template PDU_BSSAP tr_BSSMAP_CipherModeCompl(template OCT1 alg := ?) modifies tr_BSSAP_BSSMAP := {
 	pdu := {
 		bssmap := {