1.获取到富文本装着数据的对象
let quill = that.$refs.myQuillEditorForContent.quill
2.获取光标所在的位置
let length = that.$refs.myQuillEditorForContent.quill.selection.savedRange.index
3.把图片插到光标的地方(第三个参数是图片的url)
quill.insertEmbed(length, 'image', that.tempUrl)
4.把光标移到图片的后面
quill.setSelection(length + 1)