im初始化的时候调用create接口，接口中第二个参数传入
options:RCIMIWEngineOptions
const options: RCIMIWEngineOptions = {
naviServer: navigate,
fileServer: file
};
imEngine = RCIMIWEngine.create(key, options); 详情查看：https://www.rongcloud.cn/?utm_source=SEO&utm_term=helloworld
