[feature] Format the code and improve Mini Program authorization to o… (#473)

* [feature] Format the code and improve Mini Program authorization to obtain openid（miniprogram/auth/auth.go Code2Session）

* [feature] CheckEncryptedData (https://developers.weixin.qq.com/miniprogram/dev/api-backend/open-api/user-info/auth.checkEncryptedData.html)

* upgrade json error

* upgrade json error

Co-authored-by: houseme <houseme@outlook.com>

miniprogram/urllink/urllink.go

@@ -51,7 +51,6 @@ type ULResult struct {
 
 // Generate 生成url link
 func (u *URLLink) Generate(params *ULParams) (string, error) {
-	var accessToken string
 	accessToken, err := u.GetAccessToken()
 	if err != nil {
 		return "", err