Core/PacketIO: Handle QueryCountdownTimer

* Add it to battleground
* Base implementation countdowns in Group
* Fix timer sync between groups in battlegrounds
Port From (https://github.com/TrinityCore/TrinityCore/commit/6ed8b5c9077aba788ff5bc51f2652109bfea6175)

Source/Framework/Constants/GroupConst.cs

@@ -166,4 +166,11 @@ namespace Framework.Constants
 
         Max
     }
+
+    public enum CountdownTimerType
+    {
+        Pvp = 0,
+        ChallengeMode = 1,
+        PlayerCountdown = 2
+    }
 }

Source/Framework/Constants/SharedConst.cs

@@ -1888,13 +1888,6 @@ namespace Framework.Constants
         Max
     }
 
-    public enum TimerType
-    {
-        Pvp = 0,
-        ChallengerMode = 1,
-        PlayerCountdown = 2
-    }
-
     public enum GameError : uint
     {
         System = 0,