Add base system configuration commands for agent-wdd

- Implemented new base commands for system configuration:
  * swap: Disable system swap
  * selinux: Disable SELinux
  * firewall: Stop and disable firewalld and ufw
  * sysconfig: Modify system sysctl configuration
  * ssh: Add SSH-related subcommands (key, port, config)

- Updated Config.go to initialize ConfigCache with default values
- Added new utility functions in FileUtils.go for file content manipulation
- Extended Excutor.go with HardCodeCommandExecutor method

agent-wdd/config/Config.go

@@ -12,7 +12,19 @@ import (
 
 var WddConfigFilePath = "/usr/local/etc/wdd/agent-wdd-config.yaml"
 
-var ConfigCache *Config
+// ConfigCache 配置缓存
+var ConfigCache = &Config{
+	TimeStamp:     "",
+	ModifiedTimes: 0,
+	Agent: Agent{
+		OS:      OS{},
+		Network: Network{},
+		CPU:     CPU{},
+		Mem:     Memory{},
+		Swap:    Swap{},
+		Disks:   []Disk{},
+	},
+}
 
 func init() {
 	// 根据运行的操作系统不同, 修改 WddConfigFilePath 的位置