feat: add cloudflare ai gateway support for image & audio (#607)

* Update channel-test.go

* Update relay-audio.go

* Update relay-image.go

* chore: using a util function

---------

Co-authored-by: JustSong <songquanpeng@foxmail.com>

controller/channel-test.go

@@ -5,13 +5,14 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/gin-gonic/gin"
 	"net/http"
 	"one-api/common"
 	"one-api/model"
 	"strconv"
 	"sync"
 	"time"
+
+	"github.com/gin-gonic/gin"
 )
 
 func testChannel(channel *model.Channel, request ChatRequest) (err error, openaiErr *OpenAIError) {