feat(sys): add self-check functionality for system settings and frpc binary

utils/handlers.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/http"
 	"strconv"
+	"os"
 	"time"
 	"strings"
 
@@ -161,3 +162,8 @@ func GetCmdType(source string) string {
 func GetCmdParams(source string, param string) string {
 	return GetTextMiddle(source, "<"+param+">", "</"+param+">")
 }
+
+func IsFileExist(filePath string) bool {
+	_, err := os.Stat(filePath)
+	return !os.IsNotExist(err)
+}