Core/Conversations: Dropped time fields and calculate them using db2 data

Port From (https://github.com/TrinityCore/TrinityCore/commit/94b14e4f6355a7bab8004dcc2ecadadbc52833de)

Source/Game/DataStorage/Structs/B_Records.cs

@@ -121,4 +121,12 @@ namespace Game.DataStorage
         public ushort[] EmoteID = new ushort[3];
         public ushort[] EmoteDelay = new ushort[3];
     }
+
+    public sealed class BroadcastTextDurationRecord
+    {
+        public uint Id;
+        public int BroadcastTextID;
+        public int Locale;
+        public int Duration;
+    }
 }