fix: 修复聊天系统编译错误

- 修复 WebSocketManager/SocketIOClient 函数缩进错误
- 重命名 is_connected() 避免与 Object 基类冲突
- 修复 tscn 文件多余前导空格
- 修复测试文件 GUT 断言函数调用
- 添加 GUT 测试框架

addons/gut/double_templates/script_template.txt

@@ -0,0 +1,37 @@
+# ##############################################################################
+# Gut Doubled Script
+# ##############################################################################
+{extends}
+
+{constants}
+
+{properties}
+
+# ------------------------------------------------------------------------------
+# GUT stuff
+# ------------------------------------------------------------------------------
+var __gutdbl_values = {
+	thepath = '{path}',
+	subpath = '{subpath}',
+	stubber = {stubber_id},
+	spy = {spy_id},
+	gut = {gut_id},
+	from_singleton = '{singleton_name}',
+	is_partial = {is_partial},
+	doubled_methods = {doubled_methods},
+}
+var __gutdbl = load('res://addons/gut/double_tools.gd').new(self)
+
+# Here so other things can check for a method to know if this is a double.
+func __gutdbl_check_method__():
+	pass
+
+# Cleanup called by GUT after tests have finished.  Important for RefCounted
+# objects.  Nodes are freed, and won't have this method called on them.
+func __gutdbl_done():
+	__gutdbl = null
+	__gutdbl_values.clear()
+
+# ------------------------------------------------------------------------------
+# Doubled Methods
+# ------------------------------------------------------------------------------