Add an abstract json layout to make it's easier to change json library (#16528)

* Add an abstract json layout to make it's easier to change json library

* Fix import

* Fix import sequence

* Fix blank lines

* Fix blank lines

modules/httplib/httplib.go

@@ -24,7 +24,7 @@ import (
 	"sync"
 	"time"
 
-	jsoniter "github.com/json-iterator/go"
+	"code.gitea.io/gitea/modules/json"
 )
 
 var defaultSetting = Settings{false, "GiteaServer", 60 * time.Second, 60 * time.Second, nil, nil, nil, false}
@@ -443,7 +443,6 @@ func (r *Request) ToJSON(v interface{}) error {
 	if err != nil {
 		return err
 	}
-	json := jsoniter.ConfigCompatibleWithStandardLibrary
 	err = json.Unmarshal(data, v)
 	return err
 }