SIP_Templates: f_sip_SipUrl_to_str(): Print username if present

Since now user is printed, adapt existing user in Asterisk_Tests to use the proper field.

Change-Id: Ifb1470768222ddee1b1d96ecb9153412ed10fd42
diff --git a/library/SIP_Templates.ttcn b/library/SIP_Templates.ttcn
index 7da56bc..56404da 100644
--- a/library/SIP_Templates.ttcn
+++ b/library/SIP_Templates.ttcn
@@ -1426,7 +1426,11 @@
 }
 
 function f_sip_SipUrl_to_str(SipUrl uri) return charstring {
-	var charstring str := uri.scheme & ":" & f_sip_HostPort_to_str(uri.hostPort);
+	var charstring str := uri.scheme & ":";
+	if (ispresent(uri.userInfo)) {
+		str := str & uri.userInfo.userOrTelephoneSubscriber & "@";
+	}
+	str := str & f_sip_HostPort_to_str(uri.hostPort);
 	return str;
 }