feat(webclient): add new query_online function

There may be a loss of performance
Therefore, it is not enabled by default

config/rustdesk.go

@@ -11,6 +11,8 @@ type Rustdesk struct {
 	Key         string `mapstructure:"key"`
 	KeyFile     string `mapstructure:"key-file"`
 	Personal    int    `mapstructure:"personal"`
+	//webclient-magic-queryonline
+	WebclientMagicQueryonline int `mapstructure:"webclient-magic-queryonline"`
 }
 
 func LoadKeyFile(rustdesk *Rustdesk) {