feat(alist_v3): Optional pass UA to upstream remote (#6443)

* fix(115): Support 115 302 redirect while getting link under (nested) alist_v3 remote

* chore: simplify logic

* chore: simplify logic

* use internal UA

* add option to set if the user want their ua be passed to upstream

drivers/alist_v3/driver.go

@@ -109,11 +109,19 @@ func (d *AListV3) List(ctx context.Context, dir model.Obj, args model.ListArgs)
 
 func (d *AListV3) Link(ctx context.Context, file model.Obj, args model.LinkArgs) (*model.Link, error) {
 	var resp common.Resp[FsGetResp]
+	// if PassUAToUpsteam is true, then pass the user-agent to the upstream
+	userAgent := base.UserAgent
+	if d.PassUAToUpsteam {
+		userAgent = args.Header.Get("user-agent")
+		if userAgent == "" {
+			userAgent = base.UserAgent
+		}
+	}
 	_, err := d.request("/fs/get", http.MethodPost, func(req *resty.Request) {
 		req.SetResult(&resp).SetBody(FsGetReq{
 			Path:     file.GetPath(),
 			Password: d.MetaPassword,
-		})
+		}).SetHeader("user-agent", userAgent)
 	})
 	if err != nil {
 		return nil, err