[Hot Fix] Fix Linux compile due to missing include. (#2223)

- Not sure how Windows compiles, but Linux fails.

zone/groups.cpp

@@ -25,6 +25,7 @@
 #include "../common/packet_dump.h"
 #include "../common/string_util.h"
 #include "worldserver.h"
+#include "string_ids.h"
 
 extern EntityList entity_list;
 extern WorldServer worldserver;

zone/questmgr.cpp

@@ -37,6 +37,7 @@
 #include "zonedb.h"
 #include "zone_store.h"
 #include "dialogue_window.h"
+#include "string_ids.h"
 
 #include <iostream>
 #include <limits.h>