Gate empty-packet log under debug, add packet exclusion list

- Change empty packet log from log.Warn to log.Debug so it only
  shows when DebugMessages is enabled
- Add PacketDebugExclusions config (List<string>) to suppress
  specific packet types like KeepAlive, Ping from packet debug output
- Check exclusion in both LogIncomingPacket and LogOutgoingPacket
- Add ConfigComments resource entry for the new setting

MinecraftClient/Resources/ConfigComments/ConfigComments.Designer.cs

@@ -1541,6 +1541,15 @@ namespace MinecraftClient {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Packet types to exclude from packet debug logs, e.g. [&quot;KeepAlive&quot;, &quot;Ping&quot;]..
+        /// </summary>
+        internal static string Logging_PacketDebugExclusions {
+            get {
+                return ResourceManager.GetString("Logging.PacketDebugExclusions", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Show error messages..
         /// </summary>