Core/PacketIO: Validate utf8 in every client packet

(cherry picked from commit 0a2a96efaa)

src/server/game/Handlers/ChatHandler.cpp

@@ -41,7 +41,6 @@
 #include "Util.h"
 #include "World.h"
 #include "WorldPacket.h"
-#include <utf8.h>
 #include <algorithm>
 
 inline bool isNasty(uint8 c)
@@ -73,14 +72,6 @@ inline bool ValidateMessage(Player const* player, std::string& msg)
         }
     }
 
-    // validate utf8
-    if (!utf8::is_valid(msg.begin(), msg.end()))
-    {
-        TC_LOG_ERROR("network", "Player %s (%s) sent a message containing an invalid UTF8 sequence - blocked", player->GetName().c_str(),
-            player->GetGUID().ToString().c_str());
-        return false;
-    }
-
     // collapse multiple spaces into one
     if (sWorld->getBoolConfig(CONFIG_CHAT_FAKE_MESSAGE_PREVENTING))
     {