Fix bug with the 1st operator's message in inviation

Now it has correct agentId value

src/messenger/webim/libs/invitation.php

@@ -122,7 +122,8 @@ function invitation_invite($visitor_id, $operator) {
 	$thread->postMessage(
 		Thread::KIND_AGENT,
 		getlocal("invitation.message"),
-		$operator_name
+		$operator_name,
+		$operator['operatorid']
 	);
 
 	return $thread;