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/Settings.cs

@@ -1080,6 +1080,9 @@ namespace MinecraftClient
                 [TomlInlineComment("$Logging.PacketDebugMessages$")]
                 public bool PacketDebugMessages = false;
 
+                [TomlInlineComment("$Logging.PacketDebugExclusions$")]
+                public List<string> PacketDebugExclusions = new();
+
                 [TomlInlineComment("$Logging.ChatMessages$")]
                 public bool ChatMessages = true;