Function sendReadReceiptRequest

sendReadReceiptRequest(
    targetId: string,
    messageUId: string,
    channelId?: string,
): Promise<RCResult<void>>
发送群已读回执请求
Parameters
- targetId: string
  目标 ID
- messageUId: string
- OptionalchannelId: string
Returns Promise<RCResult<void>>
Description
实现群聊中按需获取己方发送消息的阅读状态请求。与群聊已读回执响应接口 sendReadReceiptResponseV2 配套使用。单独调用无法实现群回执能力
Example
群已读回执请求示例：
```
const targetId = 'targetId';
const messageUId = 'BS4O-QEBR-VJM6-9GPP';
const readReceiptRes = await RongIMLib.sendReadReceiptRequest(targetId, messageUId);
console.info('群已读回执请求：', readReceiptRes)
```