Function clearHistoryMessages

clearHistoryMessages(
conversation: IConversationIdentifier,
timestamp: number,
): Promise<RCResult<void>>
按时间戳删除消息
Parameters
- conversation: IConversationIdentifier
  会话
- timestamp: number
  清除时间点，该时间之前的消息将被清除
Returns Promise<RCResult<void>>
Description
根据时间戳删除指定单个会话中早于（含）指定时间戳的所有消息。
Example
按时间戳删除消息示例：
```
const conversation = {
  conversationType: RongIMLib.ConversationType.PRIVATE,
  targetId: 'targetId',
}
const timestamp = 1632728573423;
const clearRes = await RongIMLib.clearHistoryMessages(conversation, timestamp);
console.info('清除消息结果：', clearRes);
```