el-upload 传参

el-upload on-success默认带参，传index参数。

upload
    class="uploader-btn"
    action="/api/blade-resource/oss/endpoint/put-file-v1"
    methods = "post"
    :headers="headers"
    :show-file-list="false"
    :on-success="(response, file, fileList) =>handleAvatarSuccess(response, file, fileList, index)"
    if="item.src" :src="item.src" class="avatar el-upload-image">
    else class="el-icon-plus avue-upload__icon">