chore: 删除无用的项目配置和资源文件修改android key,修正godot4.3无法构建的问题

- 移除 .gitattributes 和 .gitignore 文件
- 删除 Asserts 目录下的棋盘和棋子基础资源文件

Scripts/Lib/RPMessage.cs

@@ -1,33 +0,0 @@
-using Godot;
-using Godot.Collections;
-
-namespace RPPackage {
-public class RPMessage
-{
-    public string Type { get; set; }
-    public string Cmd { get; set; }
-    public Dictionary Data { get; set; }
-    
-    public string Uid { get; set; }
-    public string Token { get; set; }
-    public string Code { get; set; }
-    public Dictionary ToDictionary()
-    {
-        var dict = new Dictionary();
-        if (Type != null)
-            dict.Add("type", Type);
-        if (Cmd != null)
-            dict.Add("cmd", Cmd);
-        if (Data != null)
-            dict.Add("data", Data);
-        
-        if (Uid != null)
-            dict.Add("uid", Uid);
-        if (Token != null)
-            dict.Add("token", Token);
-        if (Code != null)
-            dict.Add("code", Code);
-        return dict;
-    }
-}
-}